Abstract: Inside a case (1) of a culture medium exchange unit, a well plate (3) with wells (4) is disposed, and cells and a culture medium are placed into each of the wells (4) of the well plate (3) and cell culture is performed, and after a predetermined period of time, the culture medium inside each well (4) is exchanged. The well plate (3), a supply liquid contact part (8) of a supply pump (6), a supply tube (9), supply nozzles (10), discharge nozzles (17), discharge tubes (15), and discharge liquid contact parts (14) are disposed so as to be removable from the case (1) and replaceable.