PROBLEM TO BE SOLVED: To provide an endoscope apparatus capable of detecting the shape of an endoscope insertion part in configuration low in cost without making a spectral analysis by a spectroscope and suitable for miniaturization, and adjustable in hardness while reducing the diameter of the endoscope insertion part, and to provide an endoscope system and a medical apparatus.SOLUTION: The endoscope apparatus 100 having the long-sized endoscope insertion part 19 inserted in a subject, and a body operating part 17, includes hardness changing means 11 arranged in a plurality of parts along the longitudinal direction of the endoscope insertion part 19, and distortion detecting sensors used for detecting the shape of the endoscope insertion part 19. The hardness changing means 11 change the hardness of the endoscope insertion part 19 in the arranged parts of the hardness changing means 11 according to the operation of the operating part 17. The distortion detecting sensors are made of diffraction gratings formed in optical fibers, and diffract light of specific wavelength out of light introduced into the optical fibers to return the light to the light introducing side. The arranged density of the distortion detecting sensors is changed corresponding to the arranged positions of the hardness adjusting means.
