A radiotherapy apparatus comprising an irradiation head having a linear accelerator and an intra-head waveguide unit whose one end portion is electromagnetically connected to the linear accelerator, a supporting moving mechanism which supports and moves the irradiation head on predetermined first spherical coordinates, a microwave oscillator which generates microwaves to be supplied to the irradiation head, and which is placed in a stationary position, a fixed waveguide unit having one end portion electromagnetically connected to the microwave oscillator, and the other end portion positioned on the supporting moving mechanism, and a moving waveguide unit having one end portion electromagnetically connected to the other end portion of the fixed waveguide unit positioned on the supporting moving mechanism.