Recent progress on particle acceleration at supernova remnants

Supernova remnants in the Milky Way galaxy are most promising accelerators of cosmic rays showering on the Earth. I will review current unresolved problems and recent progress of both observational and theoretical works on the cosmic-ray acceleration at supernova remnants. I will focus on the fact that recent X-ray and very-high-energy gamma-ray observations tell us important information on this issue, especially on acceleration efficiency, evidence for proton acceleration, and so on.