Functional pants include a pant body, two front bands, two rhombic bands and two back bands. The two rhombic bands are disposed corresponding to the wearer's gluteus medius muscles that work to extend and lift the legs during a long-distance running. The rhombic bands are adapted to enhance the extensibility and reduce fatigue of the gluteus medius muscles. The front and back bands alternatively impart a stretching force to the wearer when the wearer's legs are repeatedly kicking and lifting during running, enabling the wearer to run with less effort. Thus, the functional pants have a significant effect on reducing fatigue, and are suitable for long-distance runners.