To provide an electric power synthesizing/distributing unit etc. which can be manufactured in a smaller size and does not require higher design accuracy.

The electric power synthesizing/distributing unit is configured with a coupler, in which earth conductors 21 and 22 are provided at a first layer 21 and a Nth layer 24 (N is an integer of 2 or more) of outer layers in a multilayer substrate and broadcloth side couplings 32 and 33 by a coplanar wave guide are used as inner layers. When arbitrary N synthesizers are connected in cascade, the electric power distribution ratio becomes 1-/N. If N is increased, a distance between a signal line and the ground surface becomes shorter. However, since the distance can be extended longer to a realizable extent, the unit can be manufactured in a smaller size and does not require higher design accuracy. Since the first layer 21 and the Nth layer 24 are made into an integrated shield structure, radiation loss can be reduced, without being affected by external influence. Other circuit can be connected easily by an input port 11 and/or an output port 13 formed with a half-divided through-hole 51.