The present invention relates to one kind of bearing with rotation sensor and motor with the bearing. The output signal of leakage magnetic flux has minimized duty ratio variation, and even if inside the use environment with externally applied leakage magnetic flux, stable sensor output may be obtained. There are detected part with alternately arranged N poles and S poles set on the rolling bearing on the rotating side; corresponding detecting part comprising magnetic sensors to generate analog output set on the rolling bearing on the fixed side; and differential output generating mechanism set to use the differential output of two adjacent magnetic sensors as the phase coding signal.