  Interstellar molecular clouds are gamma ray sources through the interactions
with cosmic ray protons followed by production of neutral pions which decay
into gamma rays. We present new NANTEN2 observations of the TeV gamma ray SNR
RXJ1713.7-3946 and the W28 region in the 12CO J=2-1, 4-3 and 7-6 emission
lines. In RXJ1713.7-3946 we confirm that the local molecular gas having
velocities around -10 km/s shows remarkably good spatial correlations with the
SNR. We show that the X ray peaks are well correlated with the molecular gas
over the whole SNR and suggest that the interactions between the SNR and the
molecular gas play an important role in cosmic ray acceleration via several
ways including magnetic field compression. The CO J=4-3 distribution towards
peak C shows a compact and dense cloud core having a size of about 1 pc as well
as a broad wing. The core shows a notable anti-correlation with the Suzaku X
ray image and is also associated with hard gamma rays as observed with HESS.
Based on these findings, we present a picture that peak C is a molecular clump
survived against the impact of the SN blast waves and is surrounded by high
energy electrons emitting the X ray. The TeV gamma ray distribution is, on the
other hand, more extended into the molecular gas, supporting the hadronic
origin of gamma ray production. W28 is one of the most outstanding star forming
regions exhibiting TeV gamma rays as identified through a comparison between
the NANTEN CO dataset and HESS gamma ray sources. In the W28 region, we show
the CO J=2-1 distribution over the whole region as well as the detailed image
of the two TeV gamma ray peaks. One of them show strong CO J=7-6 emission,
suggesting high excitation conditions in this high mass star forming core. A
pursuit for the detailed mechanism to produce gamma rays is in progress.
