The Schrodinger-Infold factorization method for salrinz eigenralue problem in quantum mechanics is very simple for the determination of the sigenvalues and oigenfunctione, without usinx power series or polguomial developments. Howerer, no general theory underlying thie method has been depuloned. It is the parpose of tho preseat paper to formulate explicit conditiona (A, R, G) ander which the method applies, and to lay down formulas which will enable one to write ont at once the solution of ans eigenvalue problem eatisfying these conditions. As illastrationa tho spherical harmonics, the Kepler problem in ordinary space and in spherical epaco, and the harmonie oscillator, are re-troated here on the basis of the theory now developed.