A method of focus measurement of the embodiment irradiates exposure light from a first direction and projects first and second line-and-space patterns on a substrate. Further, exposure light is irradiated from a second direction and third and fourth line-and-space patterns are projected on the substrate. By measuring a distance between the first and third line-and-space patterns on the substrate, a sum of a dislocated amount caused by dislocation of focus and an overlap dislocation amount between the first and third line-and-space patterns is calculated as a first dislocated amount. Further, by measuring a distance between the second and fourth line-and-space patterns on the substrate, an overlap dislocation amount between the second and fourth line-and-space patterns is calculated as a second dislocation amount. Further, based on the first and second dislocation amounts, the focus dislocation amount is calculated.