In an inspection apparatus, inspection is carried out by linearly moving a wafer while rotating the wafer with respect to light. In a case where the wafer is rotated, the velocity of flow of air in outer regions of the wafer is increased, and there is a possibility that the flow of the air in the outer regions cause particles contained in an atmosphere in the vicinity of the wafer to be adhered to the wafer. In a case where such particles are adhered to the wafer, the particles are also detected as a defect, and therefore yields and cleanliness in a semiconductor production process cannot be correctly evaluated. Therefore, it is desirable that adhesion of the particles contained in the atmosphere in the vicinity of the wafer to the wafer be reduced as much as possible. Further, it is expected that, when, for example, rotation speed of the wafer is increased or a diameter of the wafer is increased, such particles are adhered further remarkably. This point has not been satisfactorily considered in the conventional arts. The invention has a feature that a conductor such as a draft to outer regions is supplied from above a substrate while the substrate is being rotated and the supplied conductor is exhausted on outside of the substrate.