A liquid ejecting head unit includes a first flow path member with a first flow path and a second flow path member with a second flow path which is stacked on the first flow path member. A seal member connects the first and second flow paths and has a first seal part and a second seal part. The first flow path member applies a force to the first seal part in a stacking direction of the first and second flow path members. The second flow path member applies a force to the second seal part in a direction from the center of the second flow path to the outside and normal to the stacking direction. A retaining part controls expansion of the seal member in the normal direction with a control part. A drive element ejects liquid supplied through the first and the second flow paths through nozzles.