There is provided an external stereo microphone device that enables further enhancement of operational feeling achieved when microphones are reoriented.An external microphone attached to a mobile electronic device includes a pair of symmetrically-positioned microphones 60, a holder unit 40 having a pair of holders 46 symmetrically positioned so as to accommodate the pair of microphones 60 respectively and a joint 48 for joining the pair of holders 46 together, a case 14 having a substantially-cylindrical portion 20 that rotatably supports the holder unit 40 and a body 18 that accommodates a circuit board 22, and a roller 56 that revolves over an inner circumferential surface of the cylindrical portion 20 in association with rotation of the holder unit 40.