Webbing take-up device

A webbing take-up device comprising:

• a take-up device main body, that includes a spool that takes up a webbing by rotating in a take-up direction, and a lock mechanism that, by being operated, restricts rotation of the spool in a pull-out direction opposite to the take-up direction;
• and
• an acceleration sensor at which an inertial mass body is placed, the inertial mass body operating the lock mechanism by moving inertially due to a sharp deceleration of a vehicle, the acceleration sensor including a housing that is provided at the take-up device main body such that the housing is rotatable about a predetermined rotating axis with respect to the take-up device main body,
• wherein a position of the rotating axis of the housing is set at the upper side with respect to a position of a center of gravity of the housing including the inertial mass body, wherein
• the housing includes a placing portion on which a spherical body that is the inertial mass body is rollably placed, the placing portion being formed in a recessed shape that opens toward a side of the rotating axis,
• the position of the rotating axis is set such that the center of gravity of the housing including the spherical body is disposed between the placing portion and the rotating axis, and
• the position of the rotating axis is set at the upper side with respect to a position of the center of gravity of the spherical body which is in a state in which the spherical body is placed on the placing portion.