To provide an endoscope apparatus capable of easily confirming connected an external device.

A first character string drawing circuit 312 superimposes a graphic form on an observation image to create a superimposed image. The graphic form may be abstracted or encrypted and superimposed on the observation image, or the observation image or the superimposed image may be compressed to create a compressed image. The graphic form includes various forms such as characters. The graphic form is abstracted by transforming the graphic form into such a form that a third person cannot recognize the semantic content of the original graphic form. When the graphic form is characters indicative of the name of a subject, the name is transformed into initials. The graphic form is encrypted by transforming the graphic form into such a form that the third person cannot recognize the semantic content of the original graphic form. For instance, when the graphic form is characters indicative of the degree of processing, the characters are transformed into encryption codes such as bar codes or two-dimensional codes, or the characters are encrypted and transformed into encryption characters using a common key.