We establish the classical wave equation for a particle formed of a massless oscillatory elementary charge generally also traveling, and the resulting electromagnetic waves, of a generally Doppler-effected angular frequency ω, in the vacuum in three dimensions. We obtain from the solutions the total energy of the particle wave to be ε =h c ω, 2πh c being a function expressed in wave-medium parameters and identifiable as the Planck constant. In respect to the train of the waves as a whole traveling at the finite velocity of light c, ε = mc 2 represents thereby the translational kinetic energy of the wavetrain, m =h c ω/c 2 being its inertial mass and thereby the inertial mass of the particle. Based on the solutions we also write down a set of semi-empirical equations for the particle's de Broglie wave parameters. From the standpoint of overall modern experimental indications we comment on the origin of mass implied by the solution.