We investigate statistical behaviors of steady-state p-n junction leakage currents at source/drain of MOSFET devices (Ileaks) and dynamic fluctuations of Ileaks using a newly developed test circuit. The test circuit can acquire the leakage currents from 28,672 n+-p diodes in 7.7 s with 10 times averaging with the range from 0.1 fA to 23 fA. We demonstrate that two normal distributions exist in the steady-state (time averaging) Ileak distributions, which have different temperature dependency. A distribution of the activation energy which extracted from temperature dependence of Ileak is also revealed. Dynamic fluctuation of Ileak can be measured precisely with a simple configuration to execute pseudo parallel sampling among numerous samples for a long time. It can clarify a positive correlation between mean values of Ileak (<Ileak>) and amplitudes of quantum fluctuation of I leak (ΔIleak).