A correction information calculating device includes: a position information acquiring unit that acquires position information representing a position corresponding to a first diagram located inside a first photographed image; a second diagram position detecting unit that detects a position of a second diagram, that is different from the first diagram in at least one of a shape and a size, inside a second photographed image; and a correction information calculating unit that calculates correction information representing a correspondence relationship between a position of a pixel on the projection surface and a position of a pixel of an image forming element of a projector by comparing the position of the second diagram inside the second photographed image that is detected by the second diagram position detecting unit and the position of the second diagram on an original data of the second measurement image.