The present invention applies to a vacuum transfer system, and relates to an air control valve for controlling the supply of compressed air in a vacuum transfer system. More specially, the air control valve of the present invention is configured to execute a two-stage control. The two-stage control is realized by a piston operation method, in which, although the control is performed by compressed air supplied thereto, a first control unit is operated by an electronic control method, and a second control unit is operated by a pneumatic control method. In particular, the second control unit is operated by vacuum pressure supplied from the vacuum transfer system. The air control valve of this invention can realize improved operational stability, improved energy efficiency and improved operational precision.