To reduce errors in an angle detected by a magnetic sensor for detecting an angle that a direction of an external magnetic field forms with respect to a reference direction.

A magnetic sensor 1 is provided with: a first detection part 10 for calculating a first detection angle which is a detected value of a first angle that a direction of an external magnetic field in a first position forms with respect to a first direction; and a second detection part 20 for calculating a second detection angle which is a detected value of a second angle that the direction of the external magnetic field in a second position forms with respect to a second direction. The first detection angle includes a first angular error. The second detection angle includes a second angular error. The first angular error and the second angular error differ in phase by an odd number of times 1/2 of the error period.