A chair includes a seat, a backrest, four legs, and a massage device positioned in the back and/or the backrest. The massage device consists of a frame and plural units of two rows of massage rollers. Each massage roller has plural annular projections and a center hole. An elongate shaft extends through the massage rollers of each row and pivotally connected to a side plate at two ends of each row. Two side connect plates combine pivotally the massage rollers rows with the frame by means of center short shafts pivotally connected with the side connect plates. So the two rows of the massage rollers can be rotated by movement of a user's body to get massage.