To hold a living tissue in a mixed liquid containing the living tissue in just proportion and treat the living tissue.

There is provided a living tissue treating apparatus 1 comprising a flow channel 3 to flow the mixed liquid B containing the living tissue A, a treating part 4 connected to downstream of the flow channel 3 and holding and treating the living tissue A, and a liquid separation part 5 placed in the middle of the flow channel 3 and separating a liquid component C from the mixed liquid B. The living tissue A in the mixed liquid B containing the living tissue A can be held in just proportion and treated by the apparatus. The collecting work of the living tissue A from a patient can be finished by a single procedure to reduce load on the patient.