A freeze preventing valve which comprises a valve body longitudinally provided with an inserting hole at the upper part thereof in a hollow valve housing connected to a steam feed pipe, a valve element having a shaft disposed movably through the inserting hole of the valve body to be able to open an exhaust port at the lower end of the housing and to be vertically guided through the inserting hole of the housing. A collar is secured at an intermediate position on the shaft and a spring of shape memory alloy is interposed between the upper surface of a valve seat of the valve housing and the lower surface of the collar for urging the valve element to close the valve, by moving the valve element upwardly. A bias spring is mounted between the lower surface of the upper part of the valve body and the upper surface of the collar for urging the valve element to open the valve. Thus, the valve element of the freeze preventing valve is effectively operated by the both springs via the collar mounted on the shaft of the valve element, disposed in the valve body.