In the last paper, Part I, published 1956 by the same author, the nonlinear oscillation represented by the third order differential equation was discussed in the phase space whose axes were displacement x, velocity y=dx/dt and accelaration Z=d²x/dt². Hartley and Colpittz Oscillators were analized in the paper. Here, in Part II, two themes are discussed ; the first theme is the relation between the coefficient of the third order constant coefficient differential equation and its solution; the second theme is a simple numerical calculation method which we call Energy function method (E function method).