A metal heat storage apparatus comprising: a metal heat storage medium which is disposed in a ring type or in a quadrangular type; a medium insertion chamber is formed by disposing an insulating inner wall, an insulating outer wall and an insulating floor, each of which is made of an inner insulating wall body so as to insulate the metal heat storage medium, on the inner side, outer side and the floor, respectively, of the metal heat storage medium; an outer wall structure which is made of concrete to insulate the metal heat storage medium again and includes a floor, a central column, an outer wall body, and an upper cover; a infrared rays reflecting mirror which is disposed below the upper cover constituting the outer wall structure and reflects infrared rays generated from the metal heat storage medium; a heat exchanger which is spirally disposed inside the metal heat storage medium and includes a supply tube and a drain tube which are exposed to the outside of the outer wall structure; a solar heater which is buried in the metal heat storage medium; and a high-density optical input port which is installed to pass through the outer wall body and the insulating outer wall so as to provide the solar energy to the solar heater, wherein the high-density optical input port comprises a high temperature insulating pipe, a convex lens, and a reflective metal parabolic mirror, wherein the high temperature insulating pipe is installed to pass through the outer wall structure and the inner insulating wall body so as to be coupled to the solar heater, wherein the convex lens is coupled to the front end of the high temperature insulating pipe, and wherein the reflective metal parabolic mirror is installed at the focal position of the convex lens inside the high temperature insulating pipe and includes a through-hole formed in the center thereof. a metal heat storage medium which is disposed in a ring type or in a quadrangular type; a medium insertion chamber is formed by disposing an insulating inner wall, an insulating outer wall and an insulating floor, each of which is made of an inner insulating wall body so as to insulate the metal heat storage medium, on the inner side, outer side and the floor, respectively, of the metal heat storage medium; an outer wall structure which is made of concrete to insulate the metal heat storage medium again and includes a floor, a central column, an outer wall body, and an upper cover; a infrared rays reflecting mirror which is disposed below the upper cover constituting the outer wall structure and reflects infrared rays generated from the metal heat storage medium; a heat exchanger which is spirally disposed inside the metal heat storage medium and includes a supply tube and a drain tube which are exposed to the outside of the outer wall structure; a solar heater which is buried in the metal heat storage medium; and a high-density optical input port which is installed to pass through the outer wall body and the insulating outer wall so as to provide the solar energy to the solar heater, wherein the high-density optical input port comprises a high temperature insulating pipe, a convex lens, and a reflective metal parabolic mirror, wherein the high temperature insulating pipe is installed to pass through the outer wall structure and the inner insulating wall body so as to be coupled to the solar heater, wherein the convex lens is coupled to the front end of the high temperature insulating pipe, and wherein the reflective metal parabolic mirror is installed at the focal position of the convex lens inside the high temperature insulating pipe and includes a through-hole formed in the center thereof.