A terminal switching method for switching terminals, in a communication system in which HARQ processing is performed, to which a base station grants a transmission permission, from a terminal A to a terminal B includes notifying the terminal B of aborting of the transmission permission, setting a time point at which an HARQ process whose state of the HARQ processing is a retransmission waiting state with the terminal A is performed as a virtual starting point, setting a retransmission waiting window having a predetermined window length with the virtual starting point being regarded as its starting point, and notifying the terminal B of the transmission permission when there is no HARQ process having the retransmission waiting state with the terminal A, wherein the virtual starting point setting and the window setting are repeated until there is no HARQ process having the retransmission waiting state with the terminal A.