  Detailed chemical analyses of M dwarfs are scarce but necessary to constrain
the formation environment and internal structure of planets being found around
them. We present elemental abundances of 13 M dwarfs (2900 < Teff < 3500 K)
observed in the Subaru/IRD planet search project. They are mid-to-late M dwarfs
whose abundance of individual elements has not been well studied. We use the
high-resolution (~70,000) near-infrared (970-1750 nm) spectra to measure the
abundances of Na, Mg, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Sr by the line-by-line
analysis based on model atmospheres, with typical errors ranging from 0.2 dex
for [Fe/H] to 0.3-0.4 dex for other [X/H]. We measure radial velocities from
the spectra and combine them with Gaia astrometry to calculate the
Galactocentric space velocities UVW. The resulting [Fe/H] values agree with
previous estimates based on medium-resolution K-band spectroscopy, showing a
wide distribution of metallicity (-0.6 < [Fe/H] < +0.4). The abundance ratios
of individual elements [X/Fe] are generally aligned with the solar values in
all targets. While the [X/Fe] distributions are comparable to those of nearby
FGK stars, most of which belong to the thin disk population, the most
metal-poor object, GJ 699, could be a thick disk star. The UVW velocities also
support this. The results raise the prospect that near-infrared spectra of M
dwarfs obtained in the planet search projects can be used to grasp the trend of
elemental abundances and Galactic stellar population of nearby M dwarfs.
