A device for expressing milk from one or more breasts has at least one, and preferably two expressors and a pump. The expressors each have a cup for fitting on the breasts and a cup outlet to which a vacuum created by the pump can be connected. In use, the vacuum expresses the milk from the breast. The device has a vacuum adjustment and a vacuum release on each expressor. In this manner, the vacuum can be individually adjusted and released at the expressors. The pump includes a movable diaphragm in a chamber. The diaphragm is oscillated back and forth by a linear actuator motor such as a stepper motor. The motor has a shaft which moves back and forth axially, for direct linkage to the diaphragm, so that the size and weight of the pump are reduced. The expressors have a removable cap and removable cup assembly, and the cup assembly has a positively sealed liner, for easy disassembly and cleaning.