An exercise assistance apparatus comprising: a mounting unit capable of detaching from a first direction frame of a weight training rack, the mounting unit mounted on the first direction frame in parallel; a power transmission unit generating a power and transmitting the power, the power transmission unit arranged at the mounting unit; and an exercise assistance unit coupled movably to the power transmission unit, wherein the exercise assistance unit is adapted for receiving the power and exerting an external force on an exercise assistance and an exercise, wherein the exercise assistance unit includes a housing case having an enclosed shape, the housing case including an opening portion at a top surface and an ending portion coupled to the power transmission unit; at least one load detection member mounted in the housing case, wherein the at least one load detection member is adapted for detecting a load applied at an upper portion; a cover member covering the opening portion of the housing case, wherein the cover member is adapted for transferring the load to the at least one load detection member; and a microcomputer provided in the housing case or the power transmission unit, wherein the microcomputer is adapted for calculating a calculated value of an exercise assistance time and an exercise assistance strength based on an encoder signal transmitted from a driving portion of the power transmission unit generating a rotational driving force, wherein the microcomputer is adapted for calculating an external force value of the power transmission unit based on the calculated value and adapted for transmitting a control signal to the power transmission unit based on the external force value, characterized in that the exercise assistance unit further comprises: a guide rail provided in the cover member; a moving body moving along the guide rail; an installation plate fixed at an upper portion of the moving body; and a protection body covering the guide rail to protect the guide rail and exposing the installation plate. a mounting unit capable of detaching from a first direction frame of a weight training rack, the mounting unit mounted on the first direction frame in parallel; a power transmission unit generating a power and transmitting the power, the power transmission unit arranged at the mounting unit; and an exercise assistance unit coupled movably to the power transmission unit, wherein the exercise assistance unit is adapted for receiving the power and exerting an external force on an exercise assistance and an exercise, wherein the exercise assistance unit includes a housing case having an enclosed shape, the housing case including an opening portion at a top surface and an ending portion coupled to the power transmission unit; at least one load detection member mounted in the housing case, wherein the at least one load detection member is adapted for detecting a load applied at an upper portion; a cover member covering the opening portion of the housing case, wherein the cover member is adapted for transferring the load to the at least one load detection member; and a microcomputer provided in the housing case or the power transmission unit, wherein the microcomputer is adapted for calculating a calculated value of an exercise assistance time and an exercise assistance strength based on an encoder signal transmitted from a driving portion of the power transmission unit generating a rotational driving force, wherein the microcomputer is adapted for calculating an external force value of the power transmission unit based on the calculated value and adapted for transmitting a control signal to the power transmission unit based on the external force value, characterized in that a housing case having an enclosed shape, the housing case including an opening portion at a top surface and an ending portion coupled to the power transmission unit; at least one load detection member mounted in the housing case, wherein the at least one load detection member is adapted for detecting a load applied at an upper portion; a cover member covering the opening portion of the housing case, wherein the cover member is adapted for transferring the load to the at least one load detection member; and a microcomputer provided in the housing case or the power transmission unit, wherein the microcomputer is adapted for calculating a calculated value of an exercise assistance time and an exercise assistance strength based on an encoder signal transmitted from a driving portion of the power transmission unit generating a rotational driving force, wherein the microcomputer is adapted for calculating an external force value of the power transmission unit based on the calculated value and adapted for transmitting a control signal to the power transmission unit based on the external force value, characterized in that the exercise assistance unit further comprises: a guide rail provided in the cover member; a moving body moving along the guide rail; an installation plate fixed at an upper portion of the moving body; and a protection body covering the guide rail to protect the guide rail and exposing the installation plate. a guide rail provided in the cover member; a moving body moving along the guide rail; an installation plate fixed at an upper portion of the moving body; and a protection body covering the guide rail to protect the guide rail and exposing the installation plate.