In this paper, a novel flapping wing mechanism driven by a linear actuator is proposed. The linear actuator consists of a piezoelectric element and a permanent magnet. Based on the principle of impact drive mechanism, the linear actuator can move a reciprocating linear motion with a long travel range, which can be directly converted to a flapping motion via a crank-slider mechanism. In comparison with conventional flapping wing mechanisms driven by a rotary motor with a crank-rocker mechanism, no gearbox is needed in our design. Therefore, the proposed flapping wing mechanism can be made with small volume and light weight. A prototype was designed and constructed and experiments were carried out to test the performance of the flapping wing mechanism. The experimental results confirm that the designed flapping wing mechanism can obtain a continuous flapping motion by moving the linear actuator reciprocatingly.