A breast pump includes: a close-contact housing brought into contact with a breast of a lactating woman and having a protruding part, and a milk discharge hole formed on an end-side bottom surface of the protruding part； a cap connector covering an end side of the protruding part, having a spacing space between the cap connector and the protruding part, and provided with a milk discharge tube； a funnel connector on an upper side of the cap connector to have an inner space, and provided with a communication flow passage through which the inner space and the spacing space communicate； a cover to cover the inner space of the funnel connector； a flow separation membrane for vertically separating a space between the funnel connector and the cover； and an air tube through which air is allowed to flow into/out of the space between the cover and the flow separation membrane.
