Abstract: The invention relates to the field of inspecting mechanical parts, and in particular to an endoscope (1) suitable for being used for frequency inspection of a part that is difficult to access, and also to a method of using the endoscope (1), which endoscope comprises an endoscopic head (2), an image display device (3) for displaying images picked up via said endoscopic head (2), and an elongate member (4) connecting the endoscopic head (2) to the display device (3), and in which the endoscopic head (2) also includes a frequency inspection device (7) comprising at least one vibration sensor (10) for picking up a vibratory response of a subject for frequency inspection.