To provide a sprocket and a chain sludge raking device which is equipped with the sprocket reliably transmitting power to a chain.

The driving sprocket 7 engaged with the notch chain 5 includes a plurality of sprocket pins 27 engaged and meshed with a notch 21a of a side plate 21, and a plurality of sprocket teeth 29a inserted into the space S between a pair of side plates 21, and engaged and meshed with a barrel 23 when the sprocket pin 27 is disengaged with the notch 21a. This constitution makes it possible to transmit power by engaging and meshing the barrel 23 of the chain 5 with the sprocket teeth 29a even when the notch 21a comes off the sprocket pin 27. As a result, power can be securely transmitted to the chain 5.