To provide a meandering controller capable of precisely detecting meandering when conveying a beltlike body and precisely controlling meandering of the beltlike body during running and to provide a beltlike body cutting device capable of cutting in such a way that the beltlike body has satisfactory edge straight property.

This meandering controller is provided with a reflection type optical sensor 16 composed of a laser beam source for applying laser beam L for the beltlike body 10 during running while scanning and a light receiving part constituted integrally with the laser beam source so as to receive and detect reflected light R of laser beam. An edge part 2 of the beltlike body is detected based on a detection signal from the light receiving part to correct a running position of the beltlike body based on a detection position of the edge part.