  We report the results of optical spectroscopic monitoring observations of a T
Tauri star, V409 Tau. A previous photometric study indicated that this star
experienced dimming events due to the obscuration of light from the central
star with a distorted circumstellar disk. We conducted medium-resolution (R
~10,000) spectroscopic observations with 2-m Nayuta telescope at Nishi-Harima
Astronomical Observatory. Spectra were obtained in 18 nights between November
2015 and March 2016. Several absorption lines such as Ca I and Li, and the H
alpha emission line were confirmed in the spectra. The Ic-band magnitudes of
V409 Tau changed by approximately 1 magnitude during the observation epoch. The
equivalent widths of the five absorption lines are roughly constant despite
changes in the Ic-band magnitudes. We conclude that the light variation of the
star is caused by the obscuration of light from the central star with a
distorted circumstellar disk, based on the relationship between the equivalent
widths of the absorption lines and the Ic-band magnitudes. The blue component
of the H alpha emission line was dominant during the observation epoch, and an
inverse P Cygni profile was observed in eight of the spectra. The time-variable
inverse P Cygni profile of the H alpha emission line indicates unsteady mass
accretion from the circumstellar disk to the central star.
