An accelerator device having an organ structure includes: a pad configured to be pressed by a driver; a case configured to be attached to a vehicle body; an inside movable mechanism housed in the case; and an arm that passes through an opening formed in an outer wall of the case and connects the pad to the inside movable mechanism. The arm has a rectangle shape in a cross section. An entire circumference of the opening is surrounded by a protrusion protruding toward the pad. The protrusion includes an upper surface, and the upper surface has an inclination portion that slopes down rightward or leftward, when viewed from the pad.