An acceleration sensor includes a first substrate, a second substrate and a third substrate. The second substrate has a through-hole, a first contact formed on an inner surface of the through-hole, and a first bonding pad connected to the first contact. An electrically conductive ball is accommodated in the through-hole. The third substrate has a recess, a second contact formed in the recess contacting the bottom of the electrically conductive ball, and a second bonding pad connected to the second contact.