The identity of dark matter has been a mystery in astronomy, cosmology, and particle theory for about a century. We present the first dark matter search with a high-dispersion spectrograph by using WINERED at the 6.5 m Magellan Clay telescope to measure the photons from the dark matter decays. The dwarf spheroidal galaxies (dSphs) Leo V and Tucana II are observed by utilizing an object-sky-object nodding observation technique. Employing zero consistent flux data after the sky subtraction and performing Doppler shift analysis for further background subtraction, we have established one of the most stringent limits to date on dark matter lifetime in the mass range of 1.8-2.7 eV. The conservative bound is translated to the photon coupling, g_{ϕγγ} for axionlike par ticles around g_{ϕγγ}≲(2-3)×10^{-11} GeV^{-1} (10^{-10} GeV^{-1}) for the case that ultrafaint dSphs have the Navarro-Frenk-White (generalized Hernquist) dark matter profile.