The present invention relates to a control device and a control method for a variable valve timing mechanism that changes a valve timing by adjusting a rotational speed of a motor. The control device detects a phase angle RA1 based on an output of a crank angle sensor and an output of a cam angle sensor and calculates a change amount ΔRA of a rotational phase based on a difference between a rotation amount of a sprocket and a rotation amount of the motor. The control device stops calculating change amount ΔRA when a failure occurs in a motor rotation angle sensor. When a failure occurs in one of the crank angle sensor or the cam angle sensor, the control device stops calculating phase angle RA1 and calculates change amount ΔRA using a normal one of the sensors and the motor rotation angle sensor.