To obtain a webbing take-up device that can not only transmit to a take-up shaft only rotation from a motor by a clutch but is also simple and compact.A clutch of this webbing take-up device has a simply configuration where sliders 144 of a clutch body portion 114 are caused by frictional force to be retained in a case, whereby the sliders 144 and lock bars 154 are caused to relatively move and the lock bars 154 are caused by this relative movement to move to positions where they engage with or disengage from a ratchet 134. Consequently, the overall configuration of a clutch 100 can be made significantly compact (thinned) in comparison to a configuration that causes a pawl to move using an inertial disk that is large and has weight as in a conventional clutch. Thus, the overall configuration of a webbing take-up device 10 can be made compact.