A portable sound recorder has a body case, a left microphone and a right microphone held rotatably by the body case. An inwardly arcuate microphone receiving cavity is formed at each upper corner of the body case. The microphone receiving cavity is configured to elevate a rear side end of its arcuate bottom surface, and surrounds the under side and a part of the rear side of the microphone. Formed on the bottom surface of the microphone receiving cavity is a hollow portion that creates a gap between the microphone receiving cavity and the microphone, so as to prevent the reflected sound off the microphone receiving cavity from reaching the microphone. The gap is maintained by the hollow portion even when the microphone is rotated.