PROBLEM TO BE SOLVED: To provide a webbing winding device capable of absorbing energy of the size suitable for the physical constitution of an occupant and a state of a vehicle or the like. SOLUTION: Rotational acceleration of a gear 80 and a rotational jerk degree of the gear 80 connected to a spool 20 are arithmetically operated based on a detecting signal Rs outputted from a hole sensor 122. An ECU 102 changes a duty ratio of an electric field effect transistor FET1 based on this arithmetic operation result, and also returns its duty ratio to the original duty ratio. The energy of the size suitable for the physical constitution of the occupant and the state of the vehicle, can be absorbed thereby. COPYRIGHT: (C)2011,JPO&INPIT
