A circuit board detecting device and a detecting method are provided. The circuit board detecting device includes an image capture apparatus and a main unit. The image capture apparatus is coupled to the main unit to capture images of the surfaces of a sample circuit board and a test circuit board. In addition, the main unit is used to receive a sample frame and a test frame and compare the images of every object on the sample frame with the images of every object on the test frame to confirm if the test circuit board has flaws on the surface.