1. An image measurement device, comprising: an input circuitry via which a region of an image is designated; a first measurement region acquisition circuitry configured to acquire a first measurement region based on a first region designated via the input circuitry; a second measurement region acquisition circuitry configured to acquire a second measurement region based on a second region designated via the input circuitry; a distance computation circuitry configured to compute a real-space distance between the first measurement region and the second measurement region; and a linear region following circuitry configured to detect and follow an edge of the image, in accordance with an operation, inputted via the input circuitry, of displacing the first measurement region on a first object on which the first measurement region has been positioned, (i) the first measurement region acquisition circuitry acquiring a displaced first measurement region, (ii) the second measurement region acquisition circuitry acquiring a displaced second measurement region by displacing the second measurement region on a second object on which the second measurement region has been positioned, and (iii) the second measurement region being displaced on continuous edges, which are followed by the linear region following circuitry, so as to be the displaced second measurement region, the distance computation circuitry being configured to compute a real-space distance between the displaced first measurement region and the displaced second measurement region.