<p>An optical microphone is provided with: a light source (4); a first polarizer (5) for passing the straight polarization light from among the light beams emitted from the light source (4); a second polarizer (8) having a polarization plane that is different from the first polarizer (5) and for passing the straight polarization light; a sound receiving unit (7) having an opening and an acoustic medium through which acoustic signals that entered from the opening are propagated and which has a slower sound velocity than air, the sound receiving unit (7) being disposed in a manner such that the straight polarization light that passed through the first polarizer passes through the acoustic medium by cutting across a path for propagating the acoustic signals and enters the second polarizer; and a light detector (9) for converting the intensity of light that passed through the second polarizer (8) into electric signals. A different phase shift is applied to the straight polarization light that passed through the first polarizer between the first polarizer and the second polarizer in two directions that intersect one another and that are different from the polarization direction.</p>
