To prevent sensitivity from lowering on switching to non-directionality as to a variable directional condenser microphone unit capable of switching to unidirectionality or non-directionality by opening and closing a rear acoustic terminal of a unidirectional condenser microphone unit. The variable directional condenser microphone unit has a converter 20 consisting of a diaphragm 21 set up on a supporter ring 22 and a fixed pole 23 supported by a seat 24 oppositely placed via a spacer housed in a cylindrical housing 10 including a front acoustic terminal 11, the microphone unit being unidirectional in the case where a rear acoustic terminal 24a provided on the seat 24 is open and being switchable to non-directionality by blocking the rear acoustic terminal 24a, wherein an air chamber A1 for complementing non-directional components is provided on the rear acoustic terminal 24a side.