Provided is an acoustic transducer which is used by being fitted into an ear of a listener, is formed in a compact and lightweight shape, and preferably prevents re-reflection of a sound wave. An acoustic transducer 100 is formed of a film-shaped material having an expanding and contracting action and includes a cylindrical acoustic transducing element 101. The cylindrical acoustic transducing element 101 also functions as a sound guide tube. The acoustic transducing element 101 prevents re-reflection of the sound wave reflected by an eardrum when the sound wave has been generated and prevents localization phenomenon and a feeling of pressure in auditory sense. Also, since the acoustic transducing element 101 is formed in a compact and lightweight shape, the acoustic transducing element 101 generates the sound wave for directly reaching the eardrum or collects the sound at a place near the eardrum without a feeling of foreign materials in a case where a person wears the acoustic transducing element 101 the an ear.