1. A mobile terminal unit comprising: a memory unit that stores low bit rate contents data to which a delivery source information indicating a delivery source of high bit rate contents data with respect to predetermined contents is added, the low bit rate contents data containing contents corresponding to the predetermined contents of the high bit rate contents data; a delivery source detection unit that detects the delivery source of the high bit rate contents data based on the delivery source information added to the low bit rate contents data stored in the memory unit for reproducing the predetermined contents; a receiver unit that receives the high bit rate contents data from the delivery source detected by the delivery source detection unit for reproducing the predetermined contents; a reception state detection unit that detects a reception of the high bit rate contents data performed by the receiver unit; and a reproducing unit that reproduces the high bit rate contents data received by the receiver unit while the reception state detection unit detects the reception of the high bit rate contents data performed by the receiver unit, and reproduces the low bit rate contents data corresponding to the high bit rate contents data that have been unreceived from the low bit rate contents data stored in the memory unit while the reception state detection unit detects an unreceived state of the receiver unit with respect to the high bit rate contents data.