A throttle device mountable on a multiple cylinder engine having an intake port, the throttle device comprising: a first throttle body having a first intake passage formed therein; a second throttle body having a second intake passage formed therein; a throttle valve rotatably provided respectively in the first and the second intake passages; a throttle shaft supporting the throttle valve; an actuator that drives the throttle valve to open and close through the throttle shaft; a rotation transmission mechanism interposed between the actuator and the throttle shaft; a lever member serving as a displacement transmission mechanism connected to the throttle shaft and transmits a rotational displacement of the throttle shaft to a predetermined detection position; and a throttle opening degree sensor to detect the opening degree of the throttle valve via the lever member, wherein the rotation transmission mechanism is disposed at a position where the first throttle body and the second throttle body are adjacent, the actuator is disposed within an installation width of either one of the first and the second throttle bodies, and the throttle opening degree sensor is disposed within an installation width of the other one of the first and the second throttle bodies and having a movable side detection element integrally connected to one end of the throttle shaft via the lever member and a fixed side detection element supported on the other one of the first and second throttle bodies, the lever member is connected to the throttle shaft at an end portion side where the other one of the first and the second throttle bodies is not adjacent to the either one of the first and the second throttle bodies, and the lever member has radial length whereby it disposes the movable side detection element, and the throttle opening degree sensor and the rotation transmission mechanism are located apart from each other in the axial direction of the throttle shaft. a first throttle body having a first intake passage formed therein; a second throttle body having a second intake passage formed therein; a throttle valve rotatably provided respectively in the first and the second intake passages; a throttle shaft supporting the throttle valve; an actuator that drives the throttle valve to open and close through the throttle shaft; a rotation transmission mechanism interposed between the actuator and the throttle shaft; a lever member serving as a displacement transmission mechanism connected to the throttle shaft and transmits a rotational displacement of the throttle shaft to a predetermined detection position; and a throttle opening degree sensor to detect the opening degree of the throttle valve via the lever member, wherein the rotation transmission mechanism is disposed at a position where the first throttle body and the second throttle body are adjacent, the actuator is disposed within an installation width of either one of the first and the second throttle bodies, and the throttle opening degree sensor is disposed within an installation width of the other one of the first and the second throttle bodies and having a movable side detection element integrally connected to one end of the throttle shaft via the lever member and a fixed side detection element supported on the other one of the first and second throttle bodies, the lever member is connected to the throttle shaft at an end portion side where the other one of the first and the second throttle bodies is not adjacent to the either one of the first and the second throttle bodies, and the lever member has radial length whereby it disposes the movable side detection element, and the throttle opening degree sensor and the rotation transmission mechanism are located apart from each other in the axial direction of the throttle shaft.