A load state diagnosis device for a servomotor which diagnoses a load state of the servomotor rotationally driving a rotary tool in a predetermined rotational drive direction at a constant speed, comprising: a detection part that detects a rotational direction of a torque acting on the servomotor by measuring a command current value for the servomotor, wherein a positive and a negative value of the torque represent rotational directions; a determination part that determines whether or not the rotational direction of the torque detected by the detection part is consistent with the predetermined rotational drive direction; a load index output part that outputs a load index indicating the load state of the servomotor based on a determination result of the determination part; and a parameter setting part that sets a parameter related to the drive of the servomotor, wherein the parameter setting part comprises a control gain adjustment part that adjusts a control gain of a motor driver that controls the servomotor within a range in which a speed followability of the servomotor is tolerable, wherein the load index output part measures an occurrence frequency of a state in which the rotational direction of the torque is inconsistent with the predetermined rotational drive direction for a certain period and outputs the load index based on the occurrence frequency, or the load index output part calculates an integrated value of a period of a state in which the rotational direction of the torque is inconsistent with the predetermined rotational drive direction and outputs the load index based on the integrated value, and wherein the load state diagnosis device diagnoses the load state of the servomotor by assessing a relationship between the control gain of the servomotor and the load index. a detection part that detects a rotational direction of a torque acting on the servomotor by measuring a command current value for the servomotor, wherein a positive and a negative value of the torque represent rotational directions; a determination part that determines whether or not the rotational direction of the torque detected by the detection part is consistent with the predetermined rotational drive direction; a load index output part that outputs a load index indicating the load state of the servomotor based on a determination result of the determination part; and a parameter setting part that sets a parameter related to the drive of the servomotor, wherein the parameter setting part comprises a control gain adjustment part that adjusts a control gain of a motor driver that controls the servomotor within a range in which a speed followability of the servomotor is tolerable, wherein the load index output part measures an occurrence frequency of a state in which the rotational direction of the torque is inconsistent with the predetermined rotational drive direction for a certain period and outputs the load index based on the occurrence frequency, or the load index output part calculates an integrated value of a period of a state in which the rotational direction of the torque is inconsistent with the predetermined rotational drive direction and outputs the load index based on the integrated value, and wherein the load state diagnosis device diagnoses the load state of the servomotor by assessing a relationship between the control gain of the servomotor and the load index.