To reduce striking sound generated with chattering of a valve member.

A resistive element 15C that can be slidably contacted with a coil part 15A is contacted with an outer peripheral side of the coil part 15A of a spring 15 acting as a return spring for a valve body. With this action, a part of kinetic energy of the valve body generated by a displacement of the valve body is converted into heat energy without being stored as resilient energy in the spring 15 and absorbed into the surrounding atmosphere. Accordingly, since the kinetic energy of the valve body generated as the chattering of the valve body can be absorbed as heat energy, the chattering of the valve body can be attenuated. Consequently, the chattering or the like generated along with the chattering of the valve body can be reduced.