To provide a concave plane mirror use electromagnetic convergence system for converging sunlight or other electromagnetic waves.

Sunlight or other electromagnetic waves 1 reflected from a concave flat plate A(2) are converged on a concave flat plate B configured such that its curvature is facing each other, and extended long and slender in a direction vertical to the curvature. The concave flat plate B is installed in the neighborhood of the focal line of the concave flat plate A(2). The concave flat plate B is curved such that a center line connecting the centers of parabolas as cross-sections when the curvature is viewed from the side draws a parabola. The sunlight or other electromagnetic waves 1 linearly converged on the concave flat plate B can be converged on the central section of the concave flat plate A(2) since the center line draws the parabola. The device which receives the converged sunlight or other electromagnetic waves 1 is installed in the neighborhood of the center of the concave flat plate A(2).