An electric vehicle power storage system provided with a plurality of power storage element rows (ROW - ROW) composed of a plurality of power storage elements (Bat_11, Bat_12, Bat_21, Bat_22) connected in series and mounted on an electric vehicle comprising: parallel connecting switches (SW - SW) connected to the power storage element rows (ROW - ROW) in series respectively, wherein the power storage element rows (ROW - ROW) are arranged in parallel, and each parallel connecting switch (SW - SW) is configured to select the respective power storage element row (ROW - ROW) and connect to another power storage element row (ROW - ROW) in parallel, and perform connection and disconnection with respect to loads of a motor and an auxiliary machine mounted on the electric vehicle referred to as electric load a vehicle power requirement calculating unit configured to calculate a vehicle power requirement; a remaining level detecting unit configured to detect a remaining level of the power storage element row indicating the chargeable power of the power storage element row (ROW - ROW); a voltage detecting unit configured to detect a voltage of the power storage element row (ROW - ROW); and a power storage system control apparatus configured to control the parallel connection switch (SW - SW) on the basis of the vehicle power requirement, the remaining level of the power storage element row, and the voltage of the power storage element row (ROW - ROW); wherein the power storage system control apparatus connects the power storage element rows (ROW - ROW) to the electric load in the descending order in terms of the remaining level when the vehicle power requirement is equal to or larger than zero, and when the vehicle power requirement is smaller than zero, the power storage element rows (ROW - ROW) are connected to the electric load in the ascending order in terms of the remaining level; characterised in that the vehicle power requirement calculating unit calculates the vehicle power requirement using a vehicle power requirement, calculated by the power storage system control apparatus on the basis of a torque requirement by the driver and the number of motor revolutions; and an air-conditioning power requirement, calculated by using at least one of a set temperature of an air-conditioning apparatus, a cabin temperature, and a vehicle speed; the electric vehicle power storage system further comprising a torque requirement calculating unit configured to calculate the torque requirement of a driver on the basis of amounts of pressing of an accelerator pedal and a brake pedal by the driver, and number of motor revolutions detecting unit configured to detect the number of motor revolutions; wherein when the vehicle power requirement is other than zero and the vehicle speed is other than zero, the air-conditioning power requirement is set to be smaller as a variance of the remaining level of the entire power storage element rows increases. parallel connecting switches (SW - SW) connected to the power storage element rows (ROW - ROW) in series respectively, wherein the power storage element rows (ROW - ROW) are arranged in parallel, and each parallel connecting switch (SW - SW) is configured to select the respective power storage element row (ROW - ROW) and connect to another power storage element row (ROW - ROW) in parallel, and perform connection and disconnection with respect to loads of a motor and an auxiliary machine mounted on the electric vehicle referred to as electric load a vehicle power requirement calculating unit configured to calculate a vehicle power requirement; a remaining level detecting unit configured to detect a remaining level of the power storage element row indicating the chargeable power of the power storage element row (ROW - ROW); a voltage detecting unit configured to detect a voltage of the power storage element row (ROW - ROW); and a power storage system control apparatus configured to control the parallel connection switch (SW - SW) on the basis of the vehicle power requirement, the remaining level of the power storage element row, and the voltage of the power storage element row (ROW - ROW); wherein the power storage system control apparatus connects the power storage element rows (ROW - ROW) to the electric load in the descending order in terms of the remaining level when the vehicle power requirement is equal to or larger than zero, and when the vehicle power requirement is smaller than zero, the power storage element rows (ROW - ROW) are connected to the electric load in the ascending order in terms of the remaining level; characterised in that the vehicle power requirement calculating unit calculates the vehicle power requirement using a vehicle power requirement, calculated by the power storage system control apparatus on the basis of a torque requirement by the driver and the number of motor revolutions; and an air-conditioning power requirement, calculated by using at least one of a set temperature of an air-conditioning apparatus, a cabin temperature, and a vehicle speed; the electric vehicle power storage system further comprising a torque requirement calculating unit configured to calculate the torque requirement of a driver on the basis of amounts of pressing of an accelerator pedal and a brake pedal by the driver, and number of motor revolutions detecting unit configured to detect the number of motor revolutions; wherein when the vehicle power requirement is other than zero and the vehicle speed is other than zero, the air-conditioning power requirement is set to be smaller as a variance of the remaining level of the entire power storage element rows increases.