A chair includes a base, a seat, a backrest pivotally connected to a rear end of a seat frame of the seat, and a transmission mechanism including a motor, a telescopic rod actuated by the motor to move in a retracting direction and an extending direction, and a transmission plate. A connecting rod is pivotally connected between a lower end of the backrest frame and the transmission plate. The telescopic rod is directed to a position below a central portion of the seat. The transmission plate is pivoted to the central portion of the seat, the second end of the connecting rod, and the telescopic rod at different portions thereof. When the telescopic rod is retracted, the top support portion of the transmission plate presses against the seat frame to make the rear end of the seat frame move upward and forward.