An electricity storage device comprising: a first external terminal and a second external terminal for connection to an outside; an electricity storage unit capable of being charged and discharged; a first power source line disposed between a positive electrode side (B+) of the electricity storage unit and the first external terminal; a second power source line disposed between a negative electrode side of the electricity storage unit and the second external terminal; a power source circuit connected to both the first and second power source lines (L1, L2) and configured to supply an output voltage to a control circuit in an operating state; a power source control circuit configured to control the operating state and a non-operating state of the power source circuit; a first control signal generation circuit configured, based on an external voltage applied between the first external terminal and the second external terminal, to supply a first control signal to the power source control circuit to set the power source circuit in the operating state; and a second control signal generation circuit configured to generate a second control signal adapted to control the power source control circuit to maintain the power source circuit in the operating state, in which the output voltage of the power source circuit is supplied to the control unit, wherein the first control signal generation circuit includes a comparator configured to compare the external voltage to a reference voltage, characterized in that the first control signal generation circuit further includes a differentiating circuit (C, R7) configured to differentiate an output of the comparator outputted when the external voltage is larger than the reference voltage, such that the first control signal is supplied to the power source control circuit for a prescribed time only in case of a transition of the external voltage applied between the first external terminal and the second external terminal. a first external terminal and a second external terminal for connection to an outside; an electricity storage unit capable of being charged and discharged; a first power source line disposed between a positive electrode side (B+) of the electricity storage unit and the first external terminal; a second power source line disposed between a negative electrode side of the electricity storage unit and the second external terminal; a power source circuit connected to both the first and second power source lines (L1, L2) and configured to supply an output voltage to a control circuit in an operating state; a power source control circuit configured to control the operating state and a non-operating state of the power source circuit; a first control signal generation circuit configured, based on an external voltage applied between the first external terminal and the second external terminal, to supply a first control signal to the power source control circuit to set the power source circuit in the operating state; and a second control signal generation circuit configured to generate a second control signal adapted to control the power source control circuit to maintain the power source circuit in the operating state, in which the output voltage of the power source circuit is supplied to the control unit, wherein the first control signal generation circuit includes a comparator configured to compare the external voltage to a reference voltage, characterized in that the first control signal generation circuit further includes a differentiating circuit (C, R7) configured to differentiate an output of the comparator outputted when the external voltage is larger than the reference voltage, such that the first control signal is supplied to the power source control circuit for a prescribed time only in case of a transition of the external voltage applied between the first external terminal and the second external terminal.