A music session management device which manages a music session wherein a plurality of terminal devices are used comprises: a performance sound data acquisition unit which acquires performance sound data which represents performance sound of at least one performance part of a performance piece which is configured from a plurality of performance parts from at least one terminal device; a supplementary data selection unit which selects supplementary data which represents a performance sound of a part to be supplemented of the performance piece from a storage device which stores a plurality of instances of the supplementary data which represents a plurality of performance sounds of performance parts of the performance piece; and a play control unit which plays the performance sound of the performance sound data which the performance sound data acquisition unit has acquired from the terminal device and the performance sound of the supplementary data which the supplementary data selection unit has selected on another terminal.