We have demonstrated for the first time the analysis of noise properties in a 65mW, 405nm violet laser diode and also stabilized its frequency fluctuations as low as hyper coherent level. We measured the longitudinal mode behavior in some operation conditions, including the ambient temperature and optical feedback amount and so on. With some optical feedback amounts usually seen in typical optical pick-up systems, we have confirmed that the average relative intensity noise (RIN) value measures up to about -125dB/Hz, while the external cavity length dependences of the RIN show maximal and minimal spikes repeatedly at certain points where the external cavity length coincides with integral multiples of the effective internal cavity length of our sample LD. Under such circumstances, we have achieved the suppression of the optical feedback noise to about - 132dB/Hz by selecting the polarization of the feedback light. Moreover, we have proved the measured 65mW, 405nm violet laser diode sample tends to oscillate in multiple modes, so that we should carry out the single longitudinal mode operation by controlling the ambient temperature about 15°C. Thus, we have finally attained the frequency stabilization of the violet laser diode using a reference Fabry-Perot cavity based on the Pound-Drever- Hall method. As a result, we have achieved for the first time the frequency stability of 1.71×10-10 of the minimum square root of Allan variance in a 400nm type violet laser diode.