A pair of velocity modulation coils (52 a, 52b) are placed with a horizontal plane including a tube axis interposed therebetween, and a pair of magnetic substances (54a, 54b) are placed with a vertical plane including a tube axis interposed therebetween. A straight line portion (53a) of the velocity modulation coil extending substantially in parallel to the tube axis is placed between the magnetic substance and the tube axis. An interval D between the magnetic substance and the straight line portion (53a) is 1 to 3 mm. Assuming that the tube axis is a Z-axis, a size of the velocity modulation coil in a tube axis direction is L, and a position of an end of the velocity modulation coil on a side opposite to a phosphor screen in the tube axis direction is Z = 0, a center point of the pair of magnetic substances (54a, 54b) in the tube axis direction is present in a range of Z = 0.2 x L to 0.9 x L. Consequently, the sensitivity of velocity modulation can be enhanced while suppressing an increase in a driving power with a simple configuration.