Provided is a semiconductor package including a substrate including a mounting region, a first dam surrounding at least a portion of the mounting region, and a second dam spaced apart from the first dam and surrounding the first dam, a sub-semiconductor package on the mounting region of the substrate, conductive bumps between the substrate and the sub-semiconductor package and electrically connecting the substrate and the sub-semiconductor package, and an underfill material filling at least a portion of a space between the substrate and the sub-semiconductor package, and covering the conductive bumps, wherein the first dam and the second dam protrude upward from one surface of the substrate, and an inner wall surface of the first dam includes an inclined surface extending in a direction away from the second dam such that a distance from the second dam to the inclined surface increases as the inner wall surface extends downward.