This study is concerned with theoretical analysis of magneto-thermoelastic behavior of a conducting infinite cylinder of a rectangular cross-section which is placed in uniform magnetic field whose intensity varies sinusoidally in time. Eddy current field induced in the conducting rectangular cylinder is analytically derived by making use of the theory of quasi-stationary current. Analytical solution of two-dimensional temperature change in the cylinder due to the eddy current loss is derived by means of the Green function method. Deformations and stresses in plane strain state of the rectangular cylinder subjected to the associated eddy current loss and Lorentz force are derived under the condition of traction-free on the boundary surfaces by making use of Airy stress function. Numerical calculations are carried out and mechanical behaviors of thermal stresses and magnetic stress are made cleared.