  We report on the abundance analysis of Li in solar-type (G-type main
sequence) superflare stars which were found by the analysis of Kepler
photometric data. Li is a key element to understand the evolution of the
stellar convection zone which reflects the age of solar-type stars. We
performed the high dispersion spectroscopy of solar-type superflare stars with
Subaru/HDS, and confirmed that 34 stars show no evidence of binarity in our
previous study. In this study, we derived the Li abundances of these 34
objects.
  We investigate correlations of Li abundance with stellar atmospheric
parameters, rotational velocity, and superflare activities to understand the
nature of superflare stars and the possibility of the nucleosynthesis of Li by
superflares. We confirm the large dispersion in the Li abundance, and the
correlation with stellar parameters is not seen. As compared with the Li
abundance in Hyades cluster which is younger than the Sun, it is suggested that
half of the observed stars are younger than Hyades cluster. The measured value
of $v \sin i$ (projected rotational velocity) supports those objects are
younger than the Sun. However, there are some objects which show the low Li
abundance and slowly rotate on the basis of the estimated $v \sin i$ and $P$
(period of brightness variation). This result indicates that the superflare
stars are not only young stars but also old stars like our Sun. In our
observations, we could not find any evidence of Li productions by superflares.
Further research on Li isotope abundances of superflare stars would clarify the
Li production by stellar flares.
