This electrostatic-coupling contactless power supply device (1) comprises: a plurality of power-supply electrode plates (41-44) provided to a fixed unit (track member (2)); a high-frequency power source circuit (5) for supplying high-frequency power between the plurality of power supply electrode plates (41-44); a plurality of power-receiving electrode plates (61-64) for receiving the high-frequency power in a non-contacting manner opposing the respective plurality of power supply electrode plates (41-44), the power-receiving electrodes being provided to a movable unit (linear movable unit (3)) movably mounted on the fixed unit (2); and a power-receiving circuit (7) for converting the high-frequency power received by the plurality of power-receiving electrode plates (61-64) and supplying power to an electric load (8) on the movable unit (3). When the position of the movable unit (3) relative to the fixed unit (2) changes, the electrostatic capacitance (C1-C4) of a plurality of capacitors (Cds1-Cds4), which are configured from the separated opposing power supply electrode plates (41-44) and power-receiving electrode plates (61-64), change so as to complement each other. It is consequently possible to suppress any fluctuation in the electrostatic capacitance and maintain high power supply efficiency even when there is a change in the position of the movable unit (3) in relation to the fixed unit (2).