An objective is to provide an acceleration sensor element that has a high detection sensitivity and that realizes an accurate measurement of acceleration; and an acceleration sensor including this acceleration sensor element to realize a smaller size and a thinner thickness. An acceleration sensor element 10 comprises a quartz, has a thickness in a Z axis direction, and is formed in a quartz substrate 20 developed in an orthogonal XY plane. A thin-walled section of a bottom section of a concave section 28 of the quartz substrate 20 has a double-ended vibrating reed 30 in which a pair of vibration arms 31 and 35 extend in a Y axis direction. When acceleration in a Z axis direction is applied while this double-ended vibrating reed 30 having bending vibration, the acceleration is detected based on a change in a resonance frequency caused when the double-ended vibrating reed 30 deflects in the Z direction.