In a current sensor for detecting an electric current flowing in a current path, a magnetic field generating element generates a second magnetic field perpendicular to a first magnetic field generated by the electric current of the current path, and a magnetic sensor generates at least one of a first signal containing a sine value according to an angle defined between the second magnetic field and a synthetic magnetic field composed of the first magnetic field and the second magnetic field and a second signal containing a cosine value according to the angle. A signal processing unit includes a calculation circuit that calculates a tangential value according to the angle using the at least one of the first signal and the second signal, and outputs a sensor signal containing the tangential value.