Provided is a loop antenna capable of contributing to service area expansion of a wireless system using a magnetic field. This loop antenna is provided with: a main loop 1, which is an open loop connected to a signal source 5 or a reception circuit; and an amplifying loop 2, which is a closed loop having a same shape as the main loop 1. The main loop 1 and the amplifying loop 2 are disposed on a same surface of a planar board formed of an insulator, a first capacitor is connected to the main loop 1, and a second capacitor is connected to the amplifying loop.
