This device features a filter cleaning system that automatically removes dust adhering to the filter (even during continuous operation), thereby reducing filter clogging and preventing a decrease in suction power. A second filter cleaning is automatically performed when the device is turned on and off. When the power is turned on, a pre-filter collapses, compressing the damper. When the device is turned off, the pre-filter expands back to its original size, automatically shaking off the dust from the pre-filter with its expansion force. The cordless vacuum cleaner has a mechanism that prevents water from entering the motor when the liquid level reaches a certain amount. If the tank is full, the device automatically stops. Turn off the device after it has stopped and empty the tank. It is possible to easily empty it through a water drain cap.