Provided are a resonator having a good Q value and a filter using the resonator. The resonator has: a via electrode portion formed inside a dielectric substrate; a plurality of shielding conductors formed on the dielectric substrate to surround the via electrode portion; a first strip line which is connected to one end of the via electrode portion in the dielectric substrate and faces a first shielding conductor among the plurality of shielding conductors; and a second strip line which is connected to the other end of the via electrode portion in the dielectric substrate and faces a second shielding conductor among the plurality of shielding conductors.