In this paper, for application to a long distance wireless power transmission, a highly miniaturized 1-4 power divider/combiner employing periodic structure was fabricated on semiconducting silicon substrate. The 1-4 divider/combiner showed good RF performances from 1 to 25 GHz, and its size was 1.08 x 0.63 mm 2 , which is 0.14 % of the size of the one fabricated on PCB.