A semiconductor package includes a package substrate, an interposer mounted on the package substrate via first conductive bumps, first and second semiconductor devices disposed spaced apart from each other on the interposer and mounted on the interposer via second conductive bumps, and an underfill member filling a space between the first conductive bumps that are between the package substrate and the interposer. The interposer includes a central region and a peripheral region at least partially surrounding the central region. The first conductive bumps include first bump structures disposed on second bonding pads, which are in the central region and on a lower surface of the interposer, respectively, and having a circular shape. The first conductive bumps further include second bump structures disposed on second bonding pads, which are in the peripheral region and on the lower surface of the interposer, respectively, and having an elliptical shape.