A valve timing controller is driven by a motor and has a control circuit and a driving circuit. The driving circuit drives the motor according to a target rotation speed which is represented by a control signal frequency generated by the control circuit. Accordingly as the frequency becomes higher, the target rotation speed increases. When the frequency of the control signal is either lower than or equal to a first threshold frequency, or higher than or equal to a second threshold, the first threshold frequency being greater than zero and being greater than the second threshold frequency, the driving circuit stops supplying current to the motor.