In order to prevent any increase in number of blind detections and make efficient use of radio resources even when a format of downlink control information is changed in accordance with a communication environment, the present invention provides a radio communication method for generating control information by using a predetermined DCI format out of a plurality of DCI formats including a first DCI format having an uplink scheduling grant and a second DCI format having downlink scheduling assignment. When the first DCI format is extended in size, the second DCI format is added with an information field so as to have the same size as the extended first DCI format, and information to extend an existing function of the second DCI format and/or information to add a new function is added to the information field thereby to generate the control information.