A switch is replaced with a parallel resonant circuit 4. More specifically, a variable resonator includes a line part 1 that includes one or more lines and has an annular shape, at least two parallel resonant circuits 4 capable of changing a characteristic, and at least three variable reactance blocks 2 capable of changing a reactance value, in which the parallel resonant circuits 4 are electrically connected to the line part 1 at one end thereof at different positions on the line part 1, and the variable reactance blocks 2 are electrically connected to the line part 1 at predetermined intervals based on an electrical length at a resonance frequency.