A pump module includes a case and a pump located in the case for sending a solution according to changes in a volume of a space included in the pump where the solution flows in and out. The space includes first and second openings through which the solution flows in and out, the case includes third and fourth openings through which the solution flows in and out, the third and fourth openings are located at different positions, an angle between a direction in which the solution flows into the third opening and a direction in which the solution flows out from the second opening is greater than or equal to zero degrees and less than 90 degrees, the third opening and the first opening are connected by a first flow path, and the second opening and the fourth opening are connected by a second flow path.
