Left I think

Which Megaman? =P That's important; since it varies between series.

EDIT: If Classic, and for Protoman, then both are left-handed.

Is Megaman's blaster left or right handed?

Yes it is.

Bfa, being enigmatic since 2012 or earlier.

I think it's both. Maybe I should ask my younger brother about it -- he's a big Megaman fan.

No; he's left handed, though it changes for the other Megamen out there, like X or Trigger.

The problem arises when you realize that the sprites had to be mirrored in the NES days.(Or, more likely, didn't have to be mirrored, but Capcom took the easy way out. =P) Therefore, he seems ambidextrous.