A measurement support device comprising: a head including a collimator (505, 510, 510A) adapted to emit measurement auxiliary light emitted from a light source as a parallel beam; an imaging unit adapted to acquire an image of a subject, on which a spot is formed with the measurement auxiliary light emitted from the head, via an imaging optical system and an imaging element; a measurement unit adapted to measure a position of the spot on the imaging element on the basis of the image of the subject; a storage unit adapted to store information indicating a relationship between the position of the spot on the imaging element and an actual size of the subject; a marker creation unit (204, 210) adapted to acquire the information indicating the relationship from the storage unit on the basis of the measured position of the spot, and creates a marker indicating the actual size by obtaining a number of pixels corresponding to the marker on an image of the subject on the basis of the acquired information; and a display control unit (204, 210) adapted to make a display device display the image of the subject on which the spot is formed and the marker, and the marker be displayed in the vicinity of the spot in the image of the subject, wherein the head is adapted to emit measurement auxiliary light of which an optical axis has an inclination angle that is not 0 degrees with respect to an optical axis of the imaging optical system, and crosses a field angle of the imaging optical system, in a case where the optical axis of the measurement auxiliary light is projected on a plane including the optical axis of the imaging optical system, characterised in that the display control unit (204, 210) is adapted to correct the form of the marker before displaying said marker (M1A) on the display device such that an influence of distortion aberration of the imaging optical system is corrected based on the display position of the marker (M1, M1A) and on data of the distortion aberration of the imaging optical system. a head including a collimator (505, 510, 510A) adapted to emit measurement auxiliary light emitted from a light source as a parallel beam; an imaging unit adapted to acquire an image of a subject, on which a spot is formed with the measurement auxiliary light emitted from the head, via an imaging optical system and an imaging element; a measurement unit adapted to measure a position of the spot on the imaging element on the basis of the image of the subject; a storage unit adapted to store information indicating a relationship between the position of the spot on the imaging element and an actual size of the subject; a marker creation unit (204, 210) adapted to acquire the information indicating the relationship from the storage unit on the basis of the measured position of the spot, and creates a marker indicating the actual size by obtaining a number of pixels corresponding to the marker on an image of the subject on the basis of the acquired information; and a display control unit (204, 210) adapted to make a display device display the image of the subject on which the spot is formed and the marker, and the marker be displayed in the vicinity of the spot in the image of the subject, wherein the head is adapted to emit measurement auxiliary light of which an optical axis has an inclination angle that is not 0 degrees with respect to an optical axis of the imaging optical system, and crosses a field angle of the imaging optical system, in a case where the optical axis of the measurement auxiliary light is projected on a plane including the optical axis of the imaging optical system, characterised in that the display control unit (204, 210) is adapted to correct the form of the marker before displaying said marker (M1A) on the display device such that an influence of distortion aberration of the imaging optical system is corrected based on the display position of the marker (M1, M1A) and on data of the distortion aberration of the imaging optical system.