To provide a step device for a vehicle capable of increasing an area of the stepping surface of a step body also serving as a fender when it is in a step state.

The step body 10 also serving as a fender which is mounted to a vehicle body 4 can be changed in a state between the step state and a fender state. A wheel interference preventing region A surrounded by a first portion 10A positioned in front of a wheel 3, a second portion 10B positioned in the rear and a third portion 10C positioned above is formed on the step body 10 in the fender state. The third portion 10C is arranged outside the vehicle body 4 from the first and second portions 10A, 10B when the step body 10 is in the step state to be arranged to overhang outward from the vehicle body 4. A foot placing member 20 is arranged at a retreating position out of the wheel interference preventing region A when the step body 10 is in the fender state and arranged at a using position in the wheel interference preventing region A when it is in the step state, and its upper surface forms a pedaling surface 20A.