To provide a tire valve nut and a tire valve, which can prevent intrusion of water and foreign matter into a valve hole of a wheel.

A recessed portion 12 is formed on the inside periphery of the lowest end of the tire valve nut 10. An O-ring 13 is fitted in the recessed portion 12. For this reason, when the tire valve nut 10 is attached to a valve stem 20 by screwing the tire valve nut 10 after the valve stem 20 is inserted into the valve hole 31, the O-ring 13 is brought into contact with the valve hole 31. Therefore, the intrusion of water and the foreign matter into the valve hole 31 of the wheel 30 can be prevented. As a result, corrosion of the tire valve nut 10, the valve stem 20, and the valve hole 31 of the wheel 30 can be prevented.