|This article is about a/an transformation device in Kamen Rider Decade.|
The Decadriver (ディケイドライバー Dikeidoraibā) is a belt that gives Tsukasa Kadoya the ability to become Kamen Rider Decade, based around the Rider Cards. It was created alongside the Ride Booker, as well as Diend's Diendriver, by scientists of Dai-Shocker, which included Joji Yuki.
Decade returns in Kamen Rider Zi-O with an upgraded version of the Decadriver called the Neo Decadriver (ネオディケイドライバー Neo Dikeidoraibā), which is colored solid magenta and bears the symbols of all 20 Heisei Riders minus Decade and Zi-O. This version can use the powers of all Heisei Riders up to Zi-O.
The Decadriver and Ride Booker were created for Tsukasa's use, having been the Great Leader of Dai-Shocker before losing his memory. However, both items were abandoned and left to corrode before they were found by Natsumi Hikari amongst rubble during the destruction of the worlds. Recognizing them from her dream of Decade, she gave them to Tsukasa who was trapped in another dimension, with the items being restored as they passed through the dimensional wall. Taking the Kamen Ride: Decade card from the Ride Booker, Tsukasa inserted it into the Decadriver, transforming for the first time to defeat the rampaging monsters.
The Decadriver is composed of the following parts:
- Decadriver (ディケイドライバー Dikeidoraibā) - The central unit. When used, it reads the two-dimensional data sealed within a Rider Card and uses its power to manifest the armor parts and other materials in three-dimensional form. The green stone on top is called Trickster (トリックスター Torikkusutā) and is responsible for creating the Rider suits.
- Side Handles (サイドハンドル Saido Handoru) - The grips on either side of the Decadriver. When pulled they rotate the Decadriver, allowing Kamen Rider Decade to insert a Rider Card, and when pushed the driver is activated, releasing the energies stored within the Rider Card.
- Six Element (シックスエレメント Shikkusu Eremento) - The six circular units, located three on each Side Handle. As the name implies, they contain the power of the six elements (in order from left to right): earth, water, fire, wind, light, and darkness. They act as the source of the Decadriver's power, giving it the ability to manifest the Rider Cards' data in physical form. On the original Decadriver the Six Elements are colored green, red, and blue, while on Neo Decadriver all six are magenta.
- Rider's Crests (ライダーズクレスト Raidāzu Kuresuto) - The different Rider symbols imprinted onto the Decadriver. They are merely symbolic; a testimony to Kamen Rider Decade's ability to inherit the power of different Riders across different worlds.
By inserting a card into the Decadriver, Decade can invoke the cards' abilities. In Complete Form, the Decadriver is moved to the right side of his belt where Decade inserts his Final Attack Ride Cards and activates them by touching the Decadriver's window.
As seen in Kamen Rider × Super Sentai: Super Hero Taisen, along with Blade's Blay Rouzer and Ryuki's Drag Visor, the Decadriver is also compatible with at least some of the Gosei Cards used by the Tensou Sentai Goseiger. This is shown when he is given the Reflecloud card by Gosei Red to counter Kani Lazer's beam attack.
The Neo Decadriver gives Decade the ability to transform into his successors from Double to Build, as well as letting him access all of a Rider's abilities without requiring a Form Ride, as seen when he uses Agito's Flame Saber while in Ground Form and Wizard's water magic while in Flame Style.
When Kamen Rider Decade transforms into the previous Nine Heisei Riders using the Kamen Ride Cards, he still appears sporting the Decadriver in the place of their respective belts, to use his various Attack Ride cards. However when he disguised himself as Kamen Rider Ichigo, the Decadriver took on the appearance of Rider 1's Typhoon belt, unlike other Kamen Rides where the Decadriver is still present. It changed back when the Decadriver/Typhoon was struck by Captain Marvelous as Akarenger. It is unknown if this is a property of the card itself or a yet-undemonstrated ability of Decade's.
In the summer film, Decade is transformed by a Decade Final Form Ride Card into the Jumbo Decadriver (ジャンボディケイドライバー Janbo Dikeidoraibā), a larger version of the Decadriver which is worn by a Kamen Ride Card-summoned Kamen Rider J to transform into Decade Complete Form Jumbo Formation (ジャンボフォーメーション Janbo Fōmēshon). This form is identical to the usual Complete Form, apart from the fact that Decade is now many times larger, and wears the Decadriver on the front of his belt, with no K-Touch.
The name of the Decadriver is misspelt as "Decaderiver" on this card.
- Change announcement: KAMEN RIDE
- Form Change announcement: FORM RIDE
- Attack announcement: ATTACK RIDE
- Rider Form change announcement: FINAL FORM RIDE
- Final attack announcement: FINAL ATTACK RIDE
- Decade Complete announcement: FINAL KAMEN RIDE
- Decade Complete Jumbo announcement': FINAL KAMEN ATTACK FORM RIDE
Behind the scenes
DX Decadriver's unused sound
The DX Decadriver has "FINAL RIDE", and "RIDE" announcements, none of the Rider Cards released can activate these sounds.
Complete Selection Modification Decadriver's unused sounds
Released in March 2015, the CSM Decadriver contains newly-recorded transformation sounds for Double, OOO, Fourze, Wizard, Gaim and Drive, as well as some of Diend's Rider Cards. While the Diend Cards foreshadowed the eventual release of the CSM Diendriver, the sounds for the later Heisei Riders could only be accessed by "hacking" the belt (such as creating fake "cards" by drawing or printing the barcodes onto a blank slip of paper) since proper Rider Cards were never released, until the eventual reveal of the official Rider Cards of Heisei Phase 2 Riders from Double to Zi-O, in which are included in the upcoming release of the DX version of Neo Decadriver. It is also possible to use the Neo Decadriver version cards from Double to Drive on the CSM Decadriver.
- Although the Neo Decadriver as it appears in Kamen Rider Zi-O does not grant access to Zi-O's powers, the DX Neo Decadriver toy released through the Premium Bandai site has the transformation sounds as well as Kamen Ride and Final Attack Ride cards for Zi-O.
- If the Showa Riders' cards, as well as the Skull card from the CSM Decadriver is used on the DX Neo Decadriver, the transformation announcement is still retained. However, the transformation SFX of each Showa Rider of their respective cards (i.e., the Typhoon noises from 1 & 2) are omitted. 
- If the final form cards are inserted in the Neo Decadriver, the belt will say the full name of the form "<name of final form> Form!", not unlike the CSM version where it only said the name of the final form.
- While the original Decadriver would only play sound effects during a Kamen Ride transformation, the Neo Decadriver includes unique voice clips such as Kamen Rider Build's "Hagane no Moonsault!" voiced by KORBY. The DX Neo Decadriver demonstrates that this is a retroactive change, with the original nine Heisei Riders having extended transformation sounds that sometimes gain, voice clips such as Faiz's "Complete!" voiced by Takehiko Kano or Blade's "Turn Up!" voiced by Takeshi Sasaki.