  PICOLON (Pure Inorganic Crystal Observatory for LOw-energy Neutr(al)ino) aims
to search for cosmic dark matter by high purity NaI(Tl) scintillator. We
developed extremely pure NaI(Tl) crystal by hybrid purification method. The
recent result of $^{210}$Pb in our NaI(Tl) is less than 5.7 $\mu$Bq/kg. We will
report the test experiment in the low-background measurement at Kamioka
Underground Laboratory. The sensitivity for annual modulating signals and
finding dark matter particles will be discussed.
