Disclosed is a vacuum preventing device including a housing engaged to one side of an outer circumference portion of a fixed scroll to divide the area into a discharge region and a suction region, a chamber formed in the housing and having a compression hole connected to a compression region at one side therein, a suction hole connected to a suction region at the other side therein, and a discharge hole connected to a discharge region at a middle side therein, an open/close member is movably installed in the chamber to selectively connect the discharge hole to the suction hole, and an elastic member is installed in the chamber to provide an elasticity force to the open/close member.