  Using vector magnetograms obtained with the Spectro-polarimeter (SP) on
aboard Hinode satellite, we studied two helicity parameters (local twist and
current helicity) of 64 active regions occurred in the descending phase of
solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives
the following results. (1) The 34 active regions of the solar cycle 24 follow
the so-called hemispheric helicity rule, whereas the 30 active regions of the
solar cycle 23 do not. (2) When combining all 64 active regions as one sample,
they follow the hemispheric helicity sign rule as in most other observations.
(3) Despite with the so-far most accurate measurement of vector magnetic field
given by SP/Hinode, the rule is still weak with large scatters. (4) The data
show evidence of different helicity signs between strong and weak fields,
confirming previous result from a large sample of ground-based observations.
(5) With two example sunspots we show that the helicity parameters change sign
from the inner umbra to the outer penumbra, where the sign of penumbra agrees
with the sign of the active region as a whole. From these results, we speculate
that both the Sigma-effect (turbulent convection) and the dynamo have
contributed in the generation of helicity, whereas in both cases turbulence in
the convection zone has played a significant role.
