So recently I bought a Canon EOS M10 with the 15-45mm kit lens. I was thinking of buying another lens, the Canon EF M 22mm f/2 one. Do I need a lens adapter or not? Thank you.
No. EF-M is the native mount for the Canon M series, so no adapter is needed; you would need an adapter to use any non EF-M lens, including EF and EF-S lenses.