In a first rolling bearing of this X-ray tube apparatus, an ion nitriding layer is formed on a raceway surface of an inner ring, and an ion nitriding layer is formed on a raceway surface of an outer ring. As the results, surface hardness of the raceway surface of the inner ring and the raceway surface of the outer ring is enhanced, and abrasion resistance can be improved. On the other hand, in a second rolling bearing, an ion nitriding layer and a diamond-like carbon film are successively formed on a raceway surface of an inner ring, and an ion nitriding layer and a diamond-like carbon film are successively formed on a raceway surface of an outer ring. As the results, the second rolling bearing which is positioned closer to the target has a double hardening structure.