An inertial sensor includes a stopper having a first locking member extending from a flame onto a proof-mass, a first recess formed at the proof-mass, including a bottom surface, a second locking member extending from the proof-mass onto the edge of the flame, a second recess formed at the edge of the side member of the flame and a projection member projecting from the flame toward the proof-mass, wherein each of the first locking member and the projection member is disposed on the both sides of the second recess.