PURPOSE: To provide an in-line pump allowing a pressure tank to be made small in addition to dispensing with a stopping pressure switch or flow switch.

CONSTITUTION: In an in-line pump with a motor 22 provided in a pump casing and with a suction port and a discharge port disposed on the same line, a thermal protector 41 is provided to detect the temperature rise to the specified value or higher of a coil mounted internally to the motor 22, and a detection signal from the thermal protector 41 is used as a pump stopping signal.