A microphone unit includes: a partition member, including a vibration film configured to be vibrated by sound; a housing, defining an inner space, and formed with a first opening and a second opening, the inner space being divided into a first space and a second space by the partition member, the first space adapted to be communicated with an outer space via the first opening, and the second space adapted to be communicated with the outer space via the second opening; and a shutter, configured to close one of the first and second openings; and an amplifier, configured to: amplify an electric signal at a first gain when the shutter closes the one of the first and second openings; and amplify the electric signal at a second gain that is larger than the first gain when first and second openings are opened.