An accelerator device having an organ structure includes a pad, a case, an inside movable mechanism, an arm, and a cover. The pad is pressed by a driver. The case is attachable to a vehicle body and includes a front wall, a rear wall, and an opened side. The inside movable mechanism is housed in the case and includes a shaft, a pedal, and a bias member. The arm penetrates an opening of the case so as to connect the pad to the pedal. The cover covers the opened side. The case on the vehicle body includes a drain passage positioned below a lowest position of a root of the pedal in a movement track while the pedal is moved from an accelerator idle state to an accelerator full-throttle state.