PROBLEM TO BE SOLVED: To provide an object measuring apparatus capable of measuring the size of an object at the distal end of an endoscope more easily than a conventional one.SOLUTION: An object measuring apparatus includes an endoscope distal end hood 1 formed in short cylinder shape and detachably mounted such that its tip edge projects from the distal end of an endoscope 10 graduations 5 marked on the tip edge of the endoscope distal end hood 1 along a circumferential direction an imaging means connected to the proximal end side of the endoscope 10 and picking up an image of an observed object and an image of the graduations 5 of the endoscope distal end hood 1 to generate image data a pattern extracting means for extracting the image of the object and the image of the graduations 5 from the image data generated by the imaging means and a size computing means for comparing the image of the object with the image of the graduations 5 to compute the size of the object. The relative positions of the graduations 5 and the endoscope distal end are always fixed, and as a result, the graduations are easily fixed to the object. The reduced scale of the image of the observed graduations 5 is always constant, and the object size can be immediately read.
