The present invention is directed to the provision of a liquid crystal optical element that can accurately change the numerical aperture of an objective lens regardless of variations in temperature or wavelength. The liquid crystal optical element comprises a first substrate, a second substrate, a liquid crystal provided between the first and second substrates, an electrode pattern formed on one of the first and second substrates and having an aperture control region, and an opposite electrode formed on the other one of the first and second substrates, the opposite electrode being opposed to the electrode pattern for applying a voltage therebetween, wherein a plurality of electrodes, for changing refractive index and thereby causing the incident light passing through the aperture control region to diverge, are formed in the aperture control region.