A voltage fluctuation suppressing apparatus comprising: a power storage device configured to be connected to an electric power system; a basic control unit configured to control an output of the power storage device; a voltage detector configured to measure a voltage of a connection point to the electric power system; and an output control unit configured to receive an output of the voltage detector as an input, to divide a control amount to be outputted to the basic control unit into a reactive power command value (Qref) and an active power command value (Pref), and to output the reactive power command value and the active power command value (Pref); characterized in that the output control unit includes: a reactive power upper limit value calculation unit to calculate an upper limit value (Qref') of the reactive power command value (Qref), based on an inputted power factor command value (PFref), a reactive power calculation and output unit to calculate and output the reactive power command value (Qref), based on an inputted voltage command value (Vref), and an active power calculation and output unit to calculate and output the active power command value (Pref), which outputs 0 as the active power command value (Pref), when an absolute value of the control amount to be outputted to the basic control unit is not more than an absolute value of the upper limit value (Qref') of the reactive power command value (Qref), and outputs a value that is calculated from a prescribed expression and is not 0 as the active power command value (Pref), when the absolute value of the control amount exceeds the absolute value of the upper limit value (Qref') of the reactive power command value (Qref). a power storage device configured to be connected to an electric power system; a basic control unit configured to control an output of the power storage device; a voltage detector configured to measure a voltage of a connection point to the electric power system; and an output control unit configured to receive an output of the voltage detector as an input, to divide a control amount to be outputted to the basic control unit into a reactive power command value (Qref) and an active power command value (Pref), and to output the reactive power command value and the active power command value (Pref); characterized in that the output control unit includes: a reactive power upper limit value calculation unit to calculate an upper limit value (Qref') of the reactive power command value (Qref), based on an inputted power factor command value (PFref), a reactive power calculation and output unit to calculate and output the reactive power command value (Qref), based on an inputted voltage command value (Vref), and an active power calculation and output unit to calculate and output the active power command value (Pref), which outputs 0 as the active power command value (Pref), when an absolute value of the control amount to be outputted to the basic control unit is not more than an absolute value of the upper limit value (Qref') of the reactive power command value (Qref), and outputs a value that is calculated from a prescribed expression and is not 0 as the active power command value (Pref), when the absolute value of the control amount exceeds the absolute value of the upper limit value (Qref') of the reactive power command value (Qref). a reactive power upper limit value calculation unit to calculate an upper limit value (Qref') of the reactive power command value (Qref), based on an inputted power factor command value (PFref), a reactive power calculation and output unit to calculate and output the reactive power command value (Qref), based on an inputted voltage command value (Vref), and an active power calculation and output unit to calculate and output the active power command value (Pref), which outputs 0 as the active power command value (Pref), when an absolute value of the control amount to be outputted to the basic control unit is not more than an absolute value of the upper limit value (Qref') of the reactive power command value (Qref), and outputs a value that is calculated from a prescribed expression and is not 0 as the active power command value (Pref), when the absolute value of the control amount exceeds the absolute value of the upper limit value (Qref') of the reactive power command value (Qref).