Abstract: A force detection device and a robot system. A control device serving as the force detection device includes: a measuring member measuring a force acting on an articulated axes using a force sensor; an estimator estimating the forces acting on the articulated axes and based on the state quantity indicative of the driving state of a servo motor; and a corrector correcting the estimated value obtained through the estimation by the estimator. For the articulated axis provided with the force sensor, the control device determines, as the detection value of the force, the measured value obtained through the measurement performed by the measuring member, whereas for the articulated axis not provided with the force sensor, it determines, as the detection value of the force, the estimated value corrected by the corrector.