A cavity filter configured to be used in a base station antenna for mobile communication and configured to be installed on an external member, comprising: a resonance element; a first case configured to be disposed on the external member and containing the resonance element therein; and a terminal unit (20, 30) configured to be arranged passing through the first case to electrically connect an electrode pad of the external member and the resonance element, the terminal unit (20, 30) being electrically insulated from the first case; wherein the terminal unit (20, 30) comprises: a terminal insertion hole formed in a lower end surface of the first case by recessing at least a part of the first case; a pin member (230, 330) having a two-stage cylinder shape and comprising a pin portion (232, 332) disposed in the terminal insertion hole and having one end connected to the resonance element, and a terminal body portion (234, 334) extending from an opposite end of the pin portion (232, 332) and having a diameter larger than a diameter of the pin portion (232, 332), the terminal body portion (234, 334) having a cylindrical hollow socket portion (236, 336) formed therein with an opening (238, 338) towards the external member; and an elastic connector (240, 340) formed of a conductive material having elasticity and configured to be inserted into the hollow socket portion (236, 336) and to be disposed between the terminal body portion (234, 334) and the electrode pad to electrically connect the terminal body portion (234, 334) and the electrode pad, wherein the elastic connector (240, 340) is configured to be compressed to provide a contact pressure to an inner wall of the opening (238, 338) of the hollow socket portion (236, 336) and to the electrode pad, whereby the respective contact surfaces of the elastic connector (240, 340) become elastically deformed when the cavity filter is installed on the outer member. a resonance element; a first case configured to be disposed on the external member and containing the resonance element therein; and a terminal unit (20, 30) configured to be arranged passing through the first case to electrically connect an electrode pad of the external member and the resonance element, the terminal unit (20, 30) being electrically insulated from the first case; wherein the terminal unit (20, 30) comprises: a terminal insertion hole formed in a lower end surface of the first case by recessing at least a part of the first case; a pin member (230, 330) having a two-stage cylinder shape and comprising a pin portion (232, 332) disposed in the terminal insertion hole and having one end connected to the resonance element, and a terminal body portion (234, 334) extending from an opposite end of the pin portion (232, 332) and having a diameter larger than a diameter of the pin portion (232, 332), the terminal body portion (234, 334) having a cylindrical hollow socket portion (236, 336) formed therein with an opening (238, 338) towards the external member; and an elastic connector (240, 340) formed of a conductive material having elasticity and configured to be inserted into the hollow socket portion (236, 336) and to be disposed between the terminal body portion (234, 334) and the electrode pad to electrically connect the terminal body portion (234, 334) and the electrode pad, wherein the elastic connector (240, 340) is configured to be compressed to provide a contact pressure to an inner wall of the opening (238, 338) of the hollow socket portion (236, 336) and to the electrode pad, whereby the respective contact surfaces of the elastic connector (240, 340) become elastically deformed when the cavity filter is installed on the outer member. a terminal insertion hole formed in a lower end surface of the first case by recessing at least a part of the first case; a pin member (230, 330) having a two-stage cylinder shape and comprising a pin portion (232, 332) disposed in the terminal insertion hole and having one end connected to the resonance element, and a terminal body portion (234, 334) extending from an opposite end of the pin portion (232, 332) and having a diameter larger than a diameter of the pin portion (232, 332), the terminal body portion (234, 334) having a cylindrical hollow socket portion (236, 336) formed therein with an opening (238, 338) towards the external member; and an elastic connector (240, 340) formed of a conductive material having elasticity and configured to be inserted into the hollow socket portion (236, 336) and to be disposed between the terminal body portion (234, 334) and the electrode pad to electrically connect the terminal body portion (234, 334) and the electrode pad, wherein the elastic connector (240, 340) is configured to be compressed to provide a contact pressure to an inner wall of the opening (238, 338) of the hollow socket portion (236, 336) and to the electrode pad, whereby the respective contact surfaces of the elastic connector (240, 340) become elastically deformed when the cavity filter is installed on the outer member.