This paper introduces a light field microscopy (LFM) in which a microlens array is employed for information sampling of light direction. The LFM has expanded depth of field and digital refocusing ability for 3D measurement. However, the LFM has a critical drawback that spatial resolution is limited by spatial sampling determined by diameter of each microlens. To give a solution to this problem, digital refocusing and resolution improvement based on multi-image sub-pixel processing were implemented simultaneously. The resulting image was not only an in-focus image in whole field of view but also exhibited higher spatial resolution than an image obtained by conventional light field microscopy.