Microphone arrays, which are formed by arranging a plurality of microphones, are provided on a front side and a rear side of a housing, respectively. A virtual focus is set for each of the microphone arrays in a direction opposite to a direction in which sound is picked-up sound signals picked up by the plurality of microphones are delayed such that distances to the virtual focus are the same, and the delayed sound signals are synthesized. Therefore, sound in a sound-pickup area of a predetermined angle on each of the front side and the rear side can be picked up at a high level, and even though there is a noise source in areas other than the sound-pickup area, noise from the noise source is not picked up.