A keyboard-type tone plate percussion instrument which is simple in construction and light in weight and capable of easily unifying key-operation feelings and efficiently outputting well-balanced sounds. Percussion units are arranged to respectively correspond to keys and tone plates and each strike a corresponding tone plate when driven by a key depressing operation. A resonance box has resonance chambers corresponding to the tone plates and each having an opening side thereof close to a corresponding tone plate. The tone plates are constructed into a single-stage structure where they are arranged in an order of tone pitch in a direction of array of the keys so that tone plates neighboring in specific tone pitch are arranged adjacent to each other. The percussion units are constructed into a single-stage structure where they are arranged to correspond to array of the tone plates.