An optically pumped magnetometer 1 includes: a cell 2; a pump laser 7 that emits pump light; one or more pump light mirrors that cause the pump light guided in a first direction; a probe laser 8 that emits probe light; a splitting unit 12 that splits the probe light into multiple light components; one or more probe light mirrors that cause each of the probe light components guided in a second direction, which is a direction perpendicular to the first direction; a detection unit that detects each of the probe light components perpendicular to the pump light inside the cell 2; and a derivation unit that derives a magnetic field corresponding to a region where each of the probe light components and the pump light are perpendicular to each other based on a detection result of the detection unit.