To provide an air coupler with high safety capable of efficiently supplying air between two air compressors and preventing a hose tip from drastically jumping when an air hose is detached.

The tip of a body is formed into a plug shape connectable to a socket, and the rear end of the body is detachably provided to the tip of an air hose. A step is formed between a body inner face and the inner face of the plug-shaped portion, and a cylindrical slider is built in the plug-shaped portion so as to be retractable. The tip of the cylindrical slide is opened, and the rear end is closed. Stoppers are formed at both ends of the cylindrical slider, and an air communication hole is formed at a rear part of the cylindrical slider. The cylindrical slider brings the stoppers at the both ends into contact with the outer face and inner face step at the tip of the plug-shaped portion, and prevents them from being detached.