An apparatus for testing an object includes a moving unit configured to hold and move the object. A transmissive illuminating unit includes a light source generating light and a transmissive mask pattern. The transmissive mask pattern includes a first region configured to convert the light generated from the light source into a slit light, and a second region arranged in a movement direction of the object with respect to the first region to partially transmit the light generated from the light source. The transmissive illuminating unit is configured to project a measuring light, which is provided by transmitting the light generated from the light source through the transmissive mask pattern, to the object. A detecting unit is configured to receive a reflected light of the measuring light from the object and to detect a height and surface state of the object based on the reflected light.