A detection element has: first and second fixed parts; first and second vertical beams each connected at first and second ends to the first and second fixed parts, respectively; a horizontal beam connected at first and second ends to centers of the first and second vertical beams, respectively; and four arms each connected at a first end to the horizontal beam and having a weight formed on a second end. The first vertical beam has a first slit formed nearer the first fixed part with respect to its center, a second slit formed nearer the second fixed part with respect to its center, and a coupling portion between these slits. The second vertical beam has a third slit formed nearer the first fixed part with respect to its center, a fourth slit formed nearer the second fixed part with respect to its center, and a coupling portion between these slits.