Abstract. In this paper, we propose a numerical solution method for ordinary differential equation initial value problems by applying IMT-DE type variable transformations. In this method, we consider an integral equation that is equivalent to the initial value problem of ordinary differential equations. Numerical solutions are obtained by approximating the integral operators appearing in the equation with IMT-DE type numerical indefinite integral formulas. While previous studies have obtained numerical solutions by computing successive approximate solutions of the integral equation, in this paper, numerical solutions are obtained by solving the integral equation directly.