To provide a radial magnetic bearing device that is miniaturizable.

The radial magnetic bearing device includes a radial electromagnet for supporting a shaft 3 fixed to a rotor in a magnetically non-contacting manner, a displacement sensor, and a magnetic bearing driving control unit for controlling a current in the radial electromagnet. The radial electromagnet has an annular core 50 formed with a pair of N-pole protrusions 52xp, 52xm opposing each other to hold a shaft 3 of the rotor therebetween and a pair of S-pole protrusions 52yp, 52ym opposing each other to hold the shaft 3 therebetween, and four electromagnet coils 53 wound on the pair of N-pole protrusions 52xp, 52xm and the pair of S-pole protrusions 52yp, 52ym, respectively. The magnetic bearing driving control unit controls a current flowing in the four electromagnet coils 53 so that magnetic flux lines coming out of the pair of N-pole protrusions 52xp, 52xm enter the pair of S-pole protrusions 52yp, 52ym, based on a value detected by the displacement sensor.