A harmonic wave generator including a light source to generate a fundamental wave having a predetermined wavelength, a non-linear material to transform at least a portion of the fundamental wave generated by the light source into a harmonic wave having a shorter wavelength than the fundamental wave, and a first optical device to separate the harmonic wave generated by the non-linear material from the fundamental wave. The harmonic wave generator further includes a second optical device between the condensing lens and the non-linear material to adjust the depth of the focus of light. The harmonic wave generator is easily assembled and can be manufactured at a low cost. A harmonic wave having high power can be generated.