A user apparatus that communicates with a base station in a mobile communication system, including: a reception unit configured to receive a radio signal from the base station by a downlink control channel; and a control information detection unit configured to detect control information, addressed to the user apparatus, mapped to a predetermined area in a time frequency resource of the downlink control channel by performing blind decoding in a plurality of candidate areas which are candidates of the predetermined area, wherein, when the user apparatus performs a random access procedure, the control information detection unit performs the blind decoding in areas in which a part of areas is excluded from the plurality of candidate areas.