A non-contact power transmission device, which is capable of efficiently reducing the device size and reducing unnecessary radiation of a harmonic component from a primary side coil, is provided. The non-contact power transmission device which includes a primary side unit and a secondary side unit which house a primary side and a secondary side of a coupling transformer individually and can be separated from each other, a capacitor C1 which resonates with a primary side coil L1 is connected to the primary side coil L1 in series so that a primary side series resonance circuit is formed, an L-shaped resonance circuit which has a coil L3 and a capacitor C7 resonating with the coil L3 is inserted between the primary side series resonance circuit and a driving circuit, and the L-shaped resonance circuit is connected to the primary side series resonance circuit in series.