A robot controller according to an embodiment of the present invention comprises a base; a first link; a first actuator which drives to rotate the first link relative to the base; a first torque transmission mechanism which transmits the torque of the first actuator to the first link at a speed reducing ratio of N.sub.1; a first angular sensor which detects a rotating angle .theta..sub.M1 of the first actuator; a first angular velocity sensor which detects an angular velocity .omega..sub.A1 of the first link rotating relatively to the base; and a processor which calculates an angle of the first link relatively to the base by using a high frequency content of an integrated value of .omega..sub.A1 and a low frequency content of .theta..sub.M1*N.sub.1, the high frequency content being equal to a first frequency or higher and the low frequency content being equal to a first frequency or lower.