An angular velocity sensor including a tuning-fork sensor element made of a material exhibiting piezoelectricity to have two arms formed integrally on a base and electrodes provided on surfaces of the arms. The free end of each arm is formed with an extension projecting outward in the direction of arm vibration. The surfaces of the arms lying in the direction of vibration and the surfaces thereof lying orthogonal to thee surfaces are each provided with a single electrode. When the angular velocity sensor experiences an angular velocity owing to rotation about an axis orthogonal to the plane of the tuning fork, Coriolis forces act on the arms in the same direction as or the opposite direction from that of the vibration at that instant, thereby producing a bending moment. The direction and magnitude of the angular velocity can be determined by detecting the voltages produced by the bending moment.