A user apparatus for use in a mobile communication system includes a reception unit configured to receive a signal transmitted from a base station and obtain a parameter for determining evaluation criteria on cell reselection; a counting unit configured to count a number of cell reselections; and a measurement unit configured to measure a Doppler frequency indicative of a mobility of the user apparatus. The evaluation criteria on cell reselection are that reception signal strength of a signal transmitted from a target base station has been higher than or equal to reception signal strength of a signal transmitted from a source base station by greater than or equal to a hysteresis threshold for longer than or equal to a time to trigger. It is determined whether the evaluation criteria on cell reselection are modified and used depending on whether both first and second conditions are satisfied. The first condition is that a number of cell reselections being performed within a predefined first period (TCRmax) is greater than or equal to a predefined first threshold (NCR or NCR2). The second condition is that the Doppler frequency has been higher than or equal to a predefined second threshold (FDthresh or FDthresh2) for a predefined second period (TFD). Modification of the evaluation criteria on cell reselection comprises at least modification of the time to trigger.