An acceleration switch includes a closed container further including a cylindrical housing and a substantially circular metal header plate, a conductive lead terminal inserted through a hole of the header plate and hermetically fixed in the hole, a contact member secured to a distal end of the lead terminal and having a plurality of elastically deformable movable contacts substantially concentric about the distal end of the lead terminal, a conductive inertia ball accommodated in the container and caused to roll in the housing thereby to contact the movable contact, whereby the housing and the contact member are rendered conductive, and a braking member disposed between the movable contacts so as to be capable of urging the inertia ball in a direction of a center of the closed container. The braking member includes an elastically deformable braking portion which is extended so as to normally contact the inertia ball.