In order to provide an X-ray CT apparatus and a contrast enhanced scanning method that can obtain an image having a favorable contrast effect without re-injecting contrast medium even when a scanning position overtakes a position of the contrast medium during scanning using the contrast medium, the X-ray CT apparatus determines whether or not a current scanning position overtakes the contrast medium during main scanning, resets a scanning condition when overtaking the contrast medium, executes re-scanning under the reset scanning condition, and determines overtaking of the contrast medium based on differential data between measurement data acquired by non-contrast enhanced scanning to be performed before the main scanning and measurement data to be acquired by the main scanning. Hence, no image needs to be reconstructed during scanning to check whether or not there is a contrast effect, and the overtaking determination is performed at a high speed, which can swiftly shift to re-scanning.
