A magnetic field generator includes: an upper layer coil composed of a first conductive material and forming a loop circuit having a coil portion; a lower layer coil composed of a second conductive material and forming a loop circuit having a coil portion arranged opposite to the coil portion of the upper layer coil at a predetermined distance; and a substrate supporting the upper layer coil and the lower layer coil and having a dielectric material between the upper layer coil and the lower layer coil. High-frequency currents of opposite phases are passed through the upper layer coil and the lower layer coil, respectively, and a length per loop of the coil portion in the upper layer coil and the coil portion in the lower layer coil is matched to one wavelength of the high-frequency current.