Abstract: A servo motor includes: a driving section including a rotor and stator; an input shaft configured such that a driving force of the driving section is transferred to the input shaft, wherein the input shaft is configured to be integral and rotated with the rotor; a reduction gear configured to output the driving force from the input shaft by reducing a rotational speed of the input shaft; an output shaft configured such that the driving force which has been transferred to the input shaft is transferred to the output shaft via the reduction gear; an input encoder disc attached to the input shaft; an output encoder disc attached to the output shaft; a circuit board including a predetermined circuit pattern; an input sensor mounted on the circuit board, wherein the input sensor is oriented toward the input encoder disc; and an output sensor mounted on the circuit board, wherein the output sensor is oriented toward the output encoder disc; wherein at least one of the input sensor or the output sensor is mounted on