POWER SUPPLY DEVICE MOUNTING STRUCTURE

[PROBLEMS] To improve fixing strength of a power source apparatus mounted on a vehicle by using a reinforcing member and to reduce the size of space where a mounting structure including the reinforcing member is placed. [SOLVING MEANS] A structure for mounting a power source apparatus includes a power source apparatus (100) mounted on a vehicle (1), and a reinforcing member (40) configured to reinforce connection between the power source apparatus and a vehicle body. The power source apparatus has a power source unit (110) and a device (120, 130) fixed to an upper face of the power source unit and having a length in a front-back direction of the vehicle smaller than a length of the power source unit. The reinforcing member extends in a left-right direction of the vehicle and is fixed at different portions to the power source apparatus and the vehicle body in space (S5) above the power source unit and adjacent to the device in the front-back direction of the vehicle.