A hanger for a sash of a window to detachably engage the sash with a rail of the window, and the hanger includes a pulley assembly and a restricting assembly. The pulley assembly has a base and a plurality of pulleys mounted on the base for rotation. The pulleys engage the rail so that the pulley assembly moves in the rail. The base is provided with a slot. The sash is provided with a rod. The rod engages the slot of the pulley assembly to engage the sash with the rail, and the rod leaves the slot via a lateral opening thereof while the covering rotates for a predetermined angle. At this time, the sash is disengaged with the rail to be moved off the window.