An inspection apparatus includes a projecting unit, a first receiving unit, a second receiving unit, and a controller. The projection unit is configured to project linear light on a surface of an object. The first and second receiving units are configured to receive scattered light of the projected linear light. The controller is configured to scan the projecting unit, the first and second receiving units and determine the present or absence of a foreign substance on the surface based on intensity distribution signals output from the first and second receiving units.