A pressure-releasing breather hose 1 mounted on a urea water tank 2 is dividably constituted by a flexible joint portion 1a with an end capable of being fitted over a hose joint 3 on the tank 2, and a vertical portion 1b connected to the other end of the joint portion 1a and suspending downward along a side surface of the tank 2. The joint and vertical portions 1a and 1b are constituted by a rubber hose made of ethylene propylene diene terpolymer (EPDM) and a polyethylene pipe (resin pipe) made of high density polyethylene (HDPE), respectively.