A radiation detector includes a photoelectric conversion element array, a scintillator layer converting radiation into light, a resin frame formed on the photoelectric conversion element array, and a protective film covering the scintillator layer. The resin frame has a groove continuous with an outer edge of the protective film. The groove includes a pre-irradiation portion formed by performing scanning along the resin frame while increasing the energy of a laser beam, a main irradiation portion formed by performing scanning along the resin frame while maintaining the energy of the laser beam, and a post-irradiation portion formed by performing scanning along the resin frame while decreasing the energy of the laser beam.