A handheld electronic device including a lower body, an upper body, a sliding mechanism and a pivot axle is provided. The lower body has a carrying surface and a recess on the carrying surface. The upper body is disposed on the carrying surface. The sliding mechanism is disposed between the upper body and the lower body for driving the upper body sliding relative to the lower body. The pivot axle is disposed between the sliding mechanism and the lower body. When the handheld electronic device is transformed from a retracting state to a spreading state, an end of the upper body enters the recess, and the carrying surface of the lower body and a top surface of the upper body form an included angle.