An X-ray inspection apparatus includes a storage device, a setting device, a determining device, a calculating device and a display control device. The setting device is configured to set a hypothetical reference value that is different from an actual reference value that was used during the inspection of the articles. The determining device is configured to determine whether a contaminant exists inside each of the articles based on a result of a comparison between the hypothetical reference value and each of detection data stored in the storage device. The calculating device is configured to calculate a hypothetical contaminant existence rate as a ratio of a number of the articles in which the determining device has determined that a contaminant exists with respect to a total number of the articles. The display control device is configured to control a display section to indicate the hypothetical contaminant existence rate.