A speaker system comprising a magnetic circuit, a cylindrical shaped voice coil unit generating oscillation in the magnetic circuit, an oscillating plate extending in a circular conical shape from a outer peripheral surface of the voice coil unit, a dust cap connecting to the oscillating plate covering an open face of the voice coil unit on a side surrounded by the oscillating plate, a plurality of linking members connecting to the voice coil unit, and a detection unit. The link members extend toward a center axis of the voice coil unit. The detecting unit further comprises a first component part fastened to the linking members and positioned at the center axis of the voice coil unit closer to the voice coil unit side than the dust cap, and a second component part positioned facing the first component part and is independent of the voice coil unit such that the second component part is held between the first component part and the dust cap. The detecting unit optically detects the oscillations of the voice coil unit by means of a light that courses between the previously mentioned first component part and the second component part.