PURPOSE: To prevent damage of a tire by providing a whistle having an air valve on a tire valve with no air leakage due to a balance between the spring in a main body and tire pressure, and opening the valve in the whistle at pressure drop in the tire to whistle through flow out of air in the tire.

CONSTITUTION: When a valve main body 8 on a whistle side is screwed in a tire valve 24, the projection 23 of a valve pressure seat 21 pushes the air valve 24 to open it. Therefore, an air valve 16 is pushed by air in a tire so as to contact with the partition wall 7 of the valve main body 8. Nextly, the valve main body 8 is pushed to the right, projections 11, 11' are shifted to the left of slittings 12, and a spring 5 is compressed to lock the main body. When the pressure in the tire is lowered due to puncture, the valve 16 is opened by the force of the springs, and air in the tire is passed through the whistle 1 so as to whistle. Hereby, puncture can be quickly detected.