  We study properties of the interstellar medium, an ingredient of stars, and
star formation activity, in four nearby galaxy pairs in the early and mid
stages of interaction for both a galaxy scale and a kpc scale. The galaxy-scale
Kennicutt-Schmidt law shows that seven of eight interacting galaxies have a
star formation rate within a factor of three compared with the best-fit of the
isolated galaxies, although we have shown that molecular hydrogen gas is
efficiently produced from atomic hydrogen during the interaction in the
previous paper. The galaxy-scale specific star formation rate (sSFR) and star
formation efficiency (SFE) in interacting galaxies are comparable to those in
isolated galaxies. We also investigate SFE and the Kennicutt-Schmidt law on a
kpc scale. The spatial distributions of SFE reveal that SFE is locally
enhanced, and the enhanced regions take place asymmetrically or at off-centre
regions. The local enhancement of SFE could be induced by shock. We find that
the index of the Kennicutt-Schmidt law for the interacting galaxies in the
early stage is 1.30$\pm$0.04, which is consistent with that of the isolated
galaxies. Since CO emission, which is used in the Kennicutt-Schmidt law, is a
tracer of the amount of molecular gas, this fact suggests that dense gas, which
is more directly connected to star formation, is not changed at the early stage
of interaction.
