A valve timing controller has a shaft body as an output rotor, a torque generating system which generates the controlling torque outputted from the shaft body, and a planet carrier as an input rotor connected with the shaft body. A phase adjusting mechanism adjusts the relative rotational phase between a crankshaft and a camshaft according to the control torque inputted into the planet carrier from the shaft body. A bearing rotatably supports the planet carrier. The planet carrier forms a cylindrical input wall press-inserted in an inner circumference of the bearing. The input wall is provided with a fitting recess on its inner surface for engaging with the shaft body, the input wall is provided with a thin-wall portion of which thickness is reduced in a radial direction, and the fitting recess and the thin-wall portion are circumferentially arranged apart from each other.