We propose a high fill-factor configuration of a liquid crystal (LC) lens array fabricated by an imprinting technique. The bottom substrate of our LC lens array has a periodically concave electrode which forms an array of concave square apertures. The electrode on the imprinted concave structure produces a centro-symmetric inhomogeneous electric field which can be used for controlling the distribution of the refractive index in the LC layer. The focal length was found to vary in the range of a few centimeters. Moreover, unlike other LC lens arrays, the square aperture of each elemental lens allows for a high fill-factor. Our LC lens array is expected to be useful for various optical systems with high optical efficiency.