A radiation generating apparatus of the present invention includes an envelope 1 including a first window 2 allowing radiation to pass; a radiation tube 10 that is accommodated in the envelope 1, and includes a second window 15 allowing radiation to pass, at a position opposite to the first window 2; a radiation passing hole 21 that is thermally connected to the second window 15 and communicates with the second window 15; and a radiation shielding member 16 protruding from the second window 15 toward the first window 2. In this apparatus, a thermally conductive member 17 having a higher thermal conductivity than the radiation shielding member 16 is connected to an outer periphery of the protruding portion of the radiation shielding member 16. The simple configuration can shield unnecessary radiation, and cool the target, while facilitating reduction in weight.