An acoustic transducer has a vibrating film and a fixed film formed above an opening portion of a substrate, and at least a first sensing portion and a second sensing portion that detect sound waves using change in capacitance between a vibrating electrode provided in the vibrating film and a fixed electrode provided in the fixed film, convert the sound waves into electrical signals, and output the electrical signals. In the first sensing portion and the second sensing portion, the fixed film is used in common, and the vibrating electrode is divided into a first sensing region and a second sensing region that respectively correspond to the first sensing portion and the second sensing portion. In the first sensing portion, a protrusion portion that protrudes toward the vibrating electrode is provided on a region of the fixed film that opposes the first sensing region.