The extracted beams from the rapid cycling synchrotron (RCS) of J-PARC are delivered to the Materials and Life Science Facility (MLF) and the MR. The repetition rate of the RCS is 25 Hz and four beam pulses are for the MR and the other 87 pulses are for the MLF. Stable beam timings are required for both of the destinations. In case of the MLF, the beam has to be synchronized to the Fermi chopper, which has a tolerance of a few 100 ns. In case of the MR, the beam must be injected to the proper RF bucket with a precise phase. To realize the stable beam timing, we employ the non AC-line synchronized timing system. Also the magnetic-alloy accelerating cavities and the full digital low-level RF control system are the keys for the precise beam phase control. We present the preliminary results of the beam stability measurement.