The invention provides a vehicle body bottom structure and aims to provide a technology that inteference of parts in fixed positions during side collision is reduced and a bracket allowing free wire distribution can be arranged on a central channel. The vehicle body bottom structure is provided with: a bottom board, which is provided with the central channel that is protruded upwardly and is in the central part in the width direction of a vehicle; a lower part, which is at least arranged on the lower side of the central part; and a pair of brackets, which are arranged at hte position relative to hte lower part on the upper side of the central channel. The brackets are separately welded to the central channel in the width direction of the vehicle.