An electric power tool (400; 500) powered by at least one battery pack (10; 14; 16; 18), the electric power tool comprising: a motor configured to drive a tool; at least one battery receiving portion configured to be detachably attached to the battery pack (10; 14; 16; 18); a power supply circuit configured to electrically couple the battery pack (10; 14; 16; 18) attached to the battery receiving portion to the motor; a measuring portion configured to measure an index corresponding to a charged level of the battery pack (10; 14; 16; 18) attached to the battery receiving portion; a signal receiving portion configured to receive an alarm signal outputted from the battery pack (10; 14; 16; 18) attached to the battery receiving portion; and a controller portion configured to stop or restrict power supply to the motor based upon a measurement by the measuring portion and the alarm signal that is received, wherein the controller portion is configured to stop or restrict the power supply to the motor when the alarm signal is received or when the measurement by the measuring portion is out of a predetermined allowable range, characterized in that the controller portion is configured to: be capable of detecting whether or not the battery pack (10; 14; 16; 18) attached to the battery receiving portion has an alarm function that outputs the alarm signal, ignore the measurement by the measuring portion if the battery pack (10; 14; 16; 18) attached to the battery receiving portion has the alarm function, and stop or restrict the power supply to the motor only when the alarm signal is received. a motor configured to drive a tool; at least one battery receiving portion configured to be detachably attached to the battery pack (10; 14; 16; 18); a power supply circuit configured to electrically couple the battery pack (10; 14; 16; 18) attached to the battery receiving portion to the motor; a measuring portion configured to measure an index corresponding to a charged level of the battery pack (10; 14; 16; 18) attached to the battery receiving portion; a signal receiving portion configured to receive an alarm signal outputted from the battery pack (10; 14; 16; 18) attached to the battery receiving portion; and a controller portion configured to stop or restrict power supply to the motor based upon a measurement by the measuring portion and the alarm signal that is received, wherein the controller portion is configured to stop or restrict the power supply to the motor when the alarm signal is received or when the measurement by the measuring portion is out of a predetermined allowable range, characterized in that the controller portion is configured to: be capable of detecting whether or not the battery pack (10; 14; 16; 18) attached to the battery receiving portion has an alarm function that outputs the alarm signal, ignore the measurement by the measuring portion if the battery pack (10; 14; 16; 18) attached to the battery receiving portion has the alarm function, and stop or restrict the power supply to the motor only when the alarm signal is received. be capable of detecting whether or not the battery pack (10; 14; 16; 18) attached to the battery receiving portion has an alarm function that outputs the alarm signal, ignore the measurement by the measuring portion if the battery pack (10; 14; 16; 18) attached to the battery receiving portion has the alarm function, and stop or restrict the power supply to the motor only when the alarm signal is received.