Disclosed are semiconductor packages and their fabricating methods. The semiconductor package includes a lower structure and an upper redistribution layer. The lower structure includes a first bump layer, a lower redistribution layer, a semiconductor chip, a molding layer, a conductive pillar, and an under pad layer. The upper redistribution layer includes a second bump layer and second redistribution layers. The first redistribution layer includes a lower redistribution pattern including a first line part and a first via part. A width of the first via part increases in a direction toward the first line part from a bottom surface of the first via part. The second redistribution layer includes an upper redistribution pattern including a second line part and the second via part. A width of the second via part increases in a direction toward the second line part from a top surface of the second via part.