A pump module, which is mounted to a fuel tank, includes a sub-tank, a fuel pump and an elastic member. The sub-tank is accommodated in the fuel tank. The fuel pump is accommodated in the sub-tank to pump fuel drawn into the sub-tank. The elastic member is formed of an elastomer, and is interposed between a bottom portion of the sub-tank and a bottom portion of the fuel tank. The elastic member makes contact with fuel. The elastic member internally has spaces to release stress that arises in the elastic member due to swelling caused by contacting with fuel. The elastic member is formed in a sheet. The elastic member is mounted to the sub-tank via an outer periphery of the elastic member. The spaces are arranged in a substantially circumferential direction of the sub-tank, or are arranged in a substantially radial direction of the sub-tank.