The conversion efficiencies of optical second-harmonic generation (SHG) of light by Bessel beams and Gaussian beams in nonlinear crystals are compared. A Bessel beam, which has a quasi-nondiffractive nature, is generated by illuminating an axicon lens with a Gaussian beam. The interaction path lengths are the same for both beams, and are set to be twice the confocal parameter of the Gaussian beams. The Bessel beam is found to have greater SHG efficiency than the Gaussian beam regardless of the interaction path length and the fundamental wavelength.