According to one embodiment, an X-ray tube assembly includes a cathode includes a first non-magnetic metal member having high electrical conductivity, an anode target includes a second non-magnetic metal member having high electrical conductivity, a vacuum envelope having depressed portion depressed, and a first magnetic deflector provided outside the vacuum envelope, includes first magnetic pole pair generating the alternating magnetic field, the first magnetic pole pair being provided in close vicinity to a wall surface of the depressed portion.