An accelerator device includes: a support portion that is installable to a vehicle body; a shaft that is rotatably supported by the support portion; an operable portion that is rotatable integrally with the shaft and is depressible by a driver; an installation blocking portion that is formed in the support portion; and a full opening stopper that limits rotation of the operable portion in an accelerator opening direction when the full opening stopper contacts the operable portion. The installation blocking portion includes a space that opens toward the operable portion. A rib is formed in the space and joins between a top side inner wall and a bottom side inner wall of the space.