Front side members as a platform member of a vehicle are provided in a vehicle body on a lower side of an engine compartment to extend in a vehicle front-rear direction. A piping arrangement portion such as a piping recess is provided in an inner wall of the front side member in the vehicle front-rear direction. A liquid tube and a suction tube of a refrigerant piping are provided in the piping arrangement portion along the front side member. The liquid tube is for introducing refrigerant to an evaporator in an air conditioning unit provided in a passenger compartment, and the suction tube is for introducing refrigerant from the evaporator to a compressor provided in the engine compartment.