  We present the result of radio observations of red supergiants in the star
cluster, Stephenson's #2, and candidates for red supergiants in the star
clusters, Mercer et al. (2005)'s #4, #8, and #13, in the SiO and H$_2$O maser
lines.The Stephenson's #2 cluster and nearby aggregation at the South-West
contain more than 15 red supergiants. We detected one at the center of
Stephenson's #2 and three in the south-west aggregation in the SiO maser line,
and three of these 4 were also detected in the H2O maser line. The average
radial velocity of the 4 detected objects is 96 km s^{-1}, giving a kinematic
distance of 5.5 kpc, which locates this cluster near the base of the
Scutum-Crux spiral arm. We also detected 6 SiO emitting objects associated with
the other star clusters. In addition, mapping observations in the CO J=1--0
line toward these clusters revealed that an appreciable amount of molecular gas
still remains around Stephenson's #2 cluster in contrast to the prototypical
red-supergiant cluster, Bica et al.'s #122. It indicates that a time scale of
gas expulsion differs considerably in individual clusters.
