A semianalytical method is developed to study the free in-plane vibration of arches with any shape. The fundamental differential equations are first translated into the integral equations. By applying the approximate solution of integral equation, semianalytical solutions of the original differential equations are obtained. The solutions have discrete type expressions concerned with the equally spaced points of the arch axis or the points on the arch axis corresponding to the equally spaced points of the horizontal distance between the supports. The method is applied to analyze the free in-plane vibration of arches with nonsymmetrical axis because of the unequal height of the supports. Numerical results for the cases of nonsymmetrical, 2-hinged and fixed arches with parabolical axis are compared with the solution of the symmetric arches.