Disclosed is a speaker unit which includes a provisionally fastening mechanism provided on a side surface of a cabinet section for provisionally fastening the speaker unit to a mounting part with at least a portion of the cabinet section inserted in an opening section of the mounting part from a face side of the mounting part. The provisionally fastening mechanism includes an engagement section for provisionally fastening the speaker unit to the mounting part, and a retention section for retaining the engagement section. The engagement section is movable between an engagement position in which the engagement section engages with the mounting part and a cancellation position in which the engagement section cancels the engagement with the mounting part by being moved away from the mounting part, and the retention section retains the engagement section in the cancellation position.