To easily confirm the residual amount of an internal power source at the time of using the internal power source and to prevent sudden equipment stoppage by visually displaying the residual amount of the internal power source in a low pressure continuous suction device for medical use usable by the internal power source as well.

At the time of using this low pressure continuous suction device for discharging liquid and gas from the celom of a chest part or the like, equipment is operated normally by using an AC external power source, however, in the case of moving inside a hospital, since the external power source can not be used, the equipment is operated by using a chargeable internal power source. In such a low pressure continuous suction device, in order to recognize how much is the residual amount of the internal power source, the voltage value of the internal power source is read in a control part, analog or digital conversion is performed, signals are sent to an internal power source residual amount display part and the residual amount is displayed. Then, when charging is required, alarm sound is generated through an alarm circuit.