PUMP AND LIQUID CIRCULATING DEVICE

PROBLEM TO BE SOLVED: To suppress the heat generation of a bearing due to flow rate deterioration by stopping rotations of a rotor, when pump efficiency is deteriorated.SOLUTION: A control portion 7 for controlling feeding voltage to a stator 5 so as to keep a predetermined value of a rotation number of a rotor 3, stops a pump if the feeding voltage lowers to a threshold value or less when the feeding voltage changing according to the rotation number is compared with a predetermined threshold value, and restarts the supply of the feeding voltage after a predetermined time period has passed since the stopping, if difference between the feeding voltage and the threshold value is smaller than a predetermined difference value. In addition to the pump stopping when pump efficiency is deteriorated, an automatic restarting due to air biting is enabled.