In order to provide an X-ray CT apparatus and a scanning method, capable of improving examination throughput, and suppressing wearing of a bearing of a rotation disk, a system control device 124 of an X-ray CT apparatus 1 determines whether or not a rotation speed control operation can be performed for a standby time on the basis of an acceleration time and a deceleration time to respective rotation speeds Sn and Sm in successive scanning operations, and a standby interval time Tint, determined according to scanning conditions, decelerates the rotation disk 102 to a target low rotation speed or a rotation stoppage state if the rotation speed control operation can be performed, waits until a predetermined standby time TIdle elapses at the target low rotation speed or in the rotation stoppage state, and then increases a rotation speed of the rotation disk to a rotation speed in the next sequence.
