A speaker device is used while being attached to a helmet, and includes a speaker unit that outputs a sound, a speaker housing that includes a back wall portion covering the speaker unit from a back side, and in which a space between a back surface of the speaker unit and the back wall portion is formed as an output space for the sound output from the back surface of the speaker unit, and a duct whose internal space is communicated with the output space and that guides, to an outside of the helmet, the sound output to the output space, in which a distance between the back surface of the speaker unit and the back wall portion is smaller than a distance of the internal space of the duct in a direction in which the duct guides the sound.