An inspection apparatus comprising: a structured-light source, at least one lens and an image sensor configured to sequentially perform an operation a plurality of times for each of a plurality of structured lights having light brightness patterns that correspond to the same phase range, the operation including: radiating, by the structured-light source, a structured light of the plurality of structured lights; adjusting, by the at least one lens, an optical path of the structured light such that each light beam of the structured light corresponding to each phase of the phase range is uniformly radiated via a fist diaphragm to a whole target region on a surface of an object; and capturing, by the image sensor, a reflected light generated by the structured light being reflected from the target region and passed through a second diaphragm; and a processor electrically connected to the structured-light source, the at least one lens and the image sensor, the processor being configured to: acquire light quantity values of a plurality of reflected lights generated by the plurality of structured lights and captured by the image sensor; and derive an angle of the target region of the object with respect to a reference plane by deriving phase values of the plurality of reflected lights, based on the light quantity values of the plurality of reflected lights. a structured-light source, at least one lens and an image sensor configured to sequentially perform an operation a plurality of times for each of a plurality of structured lights having light brightness patterns that correspond to the same phase range, the operation including: radiating, by the structured-light source, a structured light of the plurality of structured lights; adjusting, by the at least one lens, an optical path of the structured light such that each light beam of the structured light corresponding to each phase of the phase range is uniformly radiated via a fist diaphragm to a whole target region radiating, by the structured-light source, a structured light of the plurality of structured lights; adjusting, by the at least one lens, an optical path of the structured light such that each light beam of the structured light corresponding to each phase of the phase range is uniformly radiated via a fist diaphragm to a whole target region on a surface of an object; and capturing, by the image sensor, a reflected light generated by the structured light being reflected from the target region and passed through a second diaphragm; and a processor electrically connected to the structured-light source, the at least one lens and the image sensor, the processor being configured to: acquire light quantity values of a plurality of reflected lights generated by the plurality of structured lights and captured by the image sensor; and derive an angle of the target region of the object with respect to a reference plane by deriving phase values of the plurality of reflected lights, based on the light quantity values of the plurality of reflected lights. acquire light quantity values of a plurality of reflected lights generated by the plurality of structured lights and captured by the image sensor; and derive an angle of the target region of the object with respect to a reference plane by deriving phase values of the plurality of reflected lights, based on the light quantity values of the plurality of reflected lights.