A waist and hip developer includes a track curving smoothly upwardly toward two distal ends thereof and having two stop members respectively located at two distal ends thereof, foot members affixed to the track for supporting the track on the floor steadily, a slide slidably coupled to the track with rollers thereof and movable back and forth along the track between the stop members, a seat rotatably supported on the slide with a ball bearing within a predetermined angle and selectively lockable to the slide with a lock screw, two grips respectively affixed to the two distal ends of the track, and a counter for counting of the number of reciprocating cycles of the slide moving by the user sitting on the seat.