A medical-system control method including a switching-instruction step in which an instruction for switching between two different control states of the bendable section provided at a distal end of the insertion section is received； an angle-difference calculation step in which the difference between the current angle of the bendable section at the time when the instruction is received and the final target angle of the bendable section in the control state after being switched is calculated； a target calculation step in which, when the calculated difference exceeds a predetermined threshold, a minute angle, smaller than the threshold, is added to the current angle to calculate the target angle, and, when the difference is less than or equal to the threshold, the difference is added to the current angle to calculate the target angle； and a driving step in which the bendable section is driven to the calculated target angle.
