To eliminate the adjustment work for compensating the dispersion of transmission characteristics and to provide a desired large power output, while suppressing temperature rise without changing the size of a core.

This power combiner is provided with the cores 3 and 4 for power synthesis provided with an oblong hole and first and second winding wires for the power combining passing through the two oblong holes, so as to turn the two oblong holes of the cores into a parallel positional relation and wound them in the same direction. The parts to be inserted to the oblong holes of the first and second winding wires are respectively constituted of linear pipe conductors 1A, 1C, 1E and 1G and 2A, 2C, 2E and 2G. To both sides of the pipe conductors, printed boards 8 and 9, where a conductive pattern is respectively formed, are attached. The parts which are at least not to be inserted to the oblong holes of the first and second winding wires are respectively constituted of the conductive patterns 1B, 1D and 1F and 2B, 2D and 2F.