It has been pointed out in particle physics that mono-energetic electrons and positrons can be produced in the annihilation of WIMP dark matter. Although the propagation through the Galaxy would broaden the line spectrum, the observed spectrum would still have the distinctive feature in the region of sub-TeV, which indicates the existence of WIMP dark matter in the Galactic halo. The recent positron fraction spectrum by the PAMELA experiment shows a significant sharp rise up to ∼100 GeV, and the electron + positron spectrum by the ATIC experiment also shows an excess in the several 100 GeV region. In order to increase greatly the amount of statistics up to higher energies, we need to observe the high-energy electrons and positrons for much longer exposure times by space utilization such as CALET on the ISS.