A PET-MRI apparatus according to an embodiment includes a static magnetic field magnet, a gradient coil, a birdcage-type radio frequency coil, and at least one PET detector. The static magnetic field magnet is configured to generate a static magnetic field. The gradient coil is configured to apply a gradient magnetic field to a subject placed in the static magnetic field. The radio frequency coil includes two end rings and a plurality of rungs arranged at intervals along a circumferential direction of the end rings and is configured to transmit a radio frequency pulse or to receive a magnetic resonance signal from the subject. Further, the PET detector is housed inside a conductor structuring the rungs of the radio frequency coil.
