To simply and easily arrange a temperature sensor so as to be thermally coupled in a state suitable for a battery surface, to detect a temperature of a battery in high accuracy by the temperature sensor, to accurately detect the battery temperature by the temperature sensor in a long time, and to facilitate assembly and maintenance.

This power source device for the vehicle is provided with a plurality of the batteries 6, a case 2 for housing the battery 6, a blower 3 for forcibly blowing the air to the battery 6 housed in the case 2, and the temperature sensor 4 brought into contact with the battery surface and detecting the battery temperature. A heat sensing part 4A of the temperature sensor 4 for detecting the battery temperature is provided with a heat sensing element 10 thermally coupled to the surface of the battery 6, and a heat insulating material 12 with a cushioning property elastically compressed and thermally insulating the heat sensing element 10 arranged on the battery surface from the cooling air, and the heat sensing element 10 is shut off from the cooling air forcibly blown by the heat insulating member 12 with the cushioning property, and the battery temperature is detected.