Unsharpness of neutron radiography (NR) image has been discussed usually two dimensionally. The unsharpness depends on size and shape of a neutron diaphragm, and on an object position and its shape. Although a circular diaphragm is often installed in the neutron collimator, rectangular diaphragms are also selected in some NR facilities. Anisotropic unsharpness is expected for these less symmetrical diaphragms. In this paper, the unsharpness is analyzed with respect to these parameters. The spatial unsharpness in depth direction should be required in case of thickness determinations and is analyzed in addition to the two dimensional unsharpness