In order to easily confirm the presence of foreign matter in oil regardless of an installation position, the invention provides a mechanical device, which includes a machine body (10) that includes anaccommodation chamber (11) in which oil is stored; a plug (20) that is attached to the bottom of the accommodation chamber (11) in a state in which an end face of a shaft (20a) faces upward; a spacermember (30) that is formed by molding a transparent member, and that is disposed in the plug (20) such that one end face (30a) faces the interior of the accommodation chamber (11); and an image capture unit (40) that is disposed in the plug (20) and that captures an image of the interior of the accommodation chamber (11) through the spacer member (30).