A unidirectional condenser microphone unit includes a unit casing formed of a metallic cylindrical body and having a front acoustic terminal on a front surface thereof and a rear acoustic terminal on a side surface thereof, an electrostatic acousto-electric converter disposed inside the unit casing, and a shield member put on the rear acoustic terminal from an inside of the unit casing in a cylindrical shape. The shield member has a length approximately equal to an inner periphery length of the unit casing and a width covering the rear acoustic terminal. Also, the shield member is formed of a metal plate having spring elasticity, and includes a large number of holes for electromagnetic shield substantially throughout the entire surface thereof.