Provided is a treatment tool exchanging device that switches and holds a plurality of treatment tools for treating a target to be treated. The treatment tool exchanging device includes a flexible insertion part into which the plurality of treatment tools are inserted and in which a plurality of treatment tool channels for defining insertion paths for the treatment tools are formed a driving part that advances each of the plurality of treatment tools, which are inserted through the treatment tool channels, within the treatment tool channel, and retracts each of the plurality of treatment tools within the treatment tool channel a manipulating part that manipulates the plurality of treatment tools to perform treatment and a control unit that controls the amount of protrusion, from the treatment tool channel of the treatment tool, which has protruded from a distal end of the treatment tool channel, among the plurality of treatment tools. The insertion part has a switching part that changes the insertion path of the treatment tool to be inserted.
