PROBLEM TO BE SOLVED: To provide an automatic peritoneal dialysis device which enables a person using the automatic peritoneal dialysis device, such as a patient, to smoothly install a cassette to be used newly on the occasion of peritoneal dialysis at a right setting position in a cassette installing part, and can improve insertability of the cassette.SOLUTION: The automatic peritoneal dialysis device includes the cassette 100 and the cassette installing part 20 which installs the cassette removably along the insertion direction SS. The cassette installing part 20 is equipped with a first latch 31 which has a slope part 41B for guiding the cassette 100 into the cassette installing part 20 along the insertion direction SS, while bringing an inside portion 99D of the first end part side of the cassette into contact, on the occasion of installing the cassette 100 in the cassette installing part 20, and with a second latch 32 which has a valley part 48 for guiding the cassette 100 into the cassette installing part 20 along the insertion direction SS in a state of the second end part side 99F of the cassette 100 being put in, on the occasion of installing the cassette 100 in the cassette installing part 20.
