An enclosure inspection and sorting method, comprising: causing thickness detecting means to determine whether or not an inspection object is thicker than a predetermined thickness while conveying the inspection object; causing X-ray inspecting means to radiate X-rays from the exterior of the inspection object and determine whether or not a suspected object is enclosed in the inspection object from the obtained X-ray image and to detect the coordinate value of the suspected object in the inspection object; causing the inspection object to move in a direction orthogonal to a conveyance direction so that the suspected object arrives at a radiating position; and radiating a terahertz wave or a millimeter wave on the suspected object in the inspection object at a timing when the suspected object is conveyed to arrive at the radiating position, when the inspection object is determined to be thinner than the predetermined thickness and is determined to have the suspected object enclosed therein, on the basis of the coordinate value, and determining whether the suspected object is a predetermined object by detecting a scattered wave, a transmitted wave, or a reflected wave of the terahertz wave or millimeter wave; wherein the method includes sorting the inspection object into: an inspection object which is determined to be thicker than the predetermined thickness, an inspection object which is determined to be thinner than the predetermined thickness and to have a predetermined object enclosed therein, and an inspection object which is determined to be thinner than the predetermined thickness and not to have a predetermined object enclosed therein. causing thickness detecting means to determine whether or not an inspection object is thicker than a predetermined thickness while conveying the inspection object; causing X-ray inspecting means to radiate X-rays from the exterior of the inspection object and determine whether or not a suspected object is enclosed in the inspection object from the obtained X-ray image and to detect the coordinate value of the suspected object in the inspection object; causing the inspection object to move in a direction orthogonal to a conveyance direction so that the suspected object arrives at a radiating position; and radiating a terahertz wave or a millimeter wave on the suspected object in the inspection object at a timing when the suspected object is conveyed to arrive at the radiating position, when the inspection object is determined to be thinner than the predetermined thickness and is determined to have the suspected object enclosed therein, on the basis of the coordinate value, and determining whether the suspected object is a predetermined object by detecting a scattered wave, a transmitted wave, or a reflected wave of the terahertz wave or millimeter wave; wherein the method includes sorting the inspection object into: an inspection object which is determined to be thicker than the predetermined thickness, an inspection object which is determined to be thinner than the predetermined thickness and to have a predetermined object enclosed therein, and an inspection object which is determined to be thinner than the predetermined thickness and not to have a predetermined object enclosed therein. an inspection object which is determined to be thicker than the predetermined thickness, an inspection object which is determined to be thinner than the predetermined thickness and to have a predetermined object enclosed therein, and an inspection object which is determined to be thinner than the predetermined thickness and not to have a predetermined object enclosed therein.