A washing machine including a housing, a control panel having an opening and a fixing protrusion, and a detergent supply device configured to be drawn into and out of the opening. The detergent supply device including a body to accommodate a detergent therein, and a handle rotatably connected to the main body and including a locking protrusion. The detergent supply device and the handle are configured to have a locked state in which the detergent supply device is drawn into the washing machine, the locking protrusion is positioned closer to the body than the fixing protrusion, and forward movement of the detergent supply device is restricted by the locking protrusion contacting the fixing protrusion, and, the handle is rotatable to move the locking protrusion thereby releasing the detergent supply device from the locked state to an open state in which forward movement of the detergent supply device through the opening is not restricted.