A transmission line is provided with a line portion with a first relative permittivity which is composed of a first dielectric and a conductor filler dispersed in the first dielectric, and a surrounding dielectric portion composed of a second dielectric with a second relative permittivity, wherein, the surrounding dielectric portion exists around the line portion in a cross section perpendicular to a direction in which electromagnetic waves transmit in the line portion, the first relative permittivity is 600 or more, and the second relative permittivity is smaller than the first relative permittivity. An electronic component has the transmission line. Further, an electronic component is provided with a resonator having a resonant frequency ranging from 1 GHz to 10 GHz, wherein, the resonator is formed by using the transmission line.