Disclosed is a template substrate for use in adjusting a focus offset to detect a defect using an optical image obtained by irradiating a substrate with light emitted from a light source. The template substrate includes a first pattern constructed with a repetitive pattern that is not resolved by the wavelength of the light source, and at least one alignment mark that is arranged on the same plane as the first pattern. The alignment mark includes a second pattern constructed with a repetitive pattern that is not resolved by the wavelength of the light source, and a programmed defect that is provided in the second pattern and not resolved by the wavelength of the light source. The alignment mark includes the second pattern, and a region, where the second pattern is not arranged but a mark used in alignment is formed by contrast with a region where the second pattern is arranged.