  We present the updated galaxy cluster catalog of the second Planck catalog of
Sunyaev-Zeldovich sources (PSZ2) through the compilation of the data for
clusters and galaxies with spectroscopically measured redshifts in the
literature. The original version of PSZ2 comprises 1653 SZ sources, of which
1203 have been validated as genuine galaxy clusters, while the remaining 450
sources are yet to be validated. To increase the number of genuine clusters in
PSZ2, we first update the validations of the cluster candidates and their
redshift information using the data compiled for the confirmed clusters and the
member galaxies in the literature. We then use the galaxy redshift data in the
fields of the remaining cluster candidates, by searching for possible member
galaxies with measured spectroscopic redshifts around the Sunyaev-Zeldovich
centroids. In this search process, we classify clusters as strong candidates if
they contain more than nine galaxies within a 4500 km s$^{-1}$ velocity range
and within 15 arcmin around the Sunyaev-Zeldovich centroids. This process
results in the validation of 139 new genuine clusters, the update of redshift
information on 399 clusters, and the identification of 10 strong candidates,
which increases the number of validated clusters up to 1334 among the 1653 SZ
sources. Our updated galaxy cluster catalog will be very useful for the studies
of galaxy formation and cosmology through the combination with other all-sky
surveys including WISE and SPHEREx.
