Ayegbeni Yakubu's third goal since his arrival on loan from Premier League side Everton and Andy King's fourth goal in his last three league games gave the Foxes a vital three points as they moved up to seventh place.
Eriksson said: "Taking three points here is never easy and I think we deserved it, I don't think Derby had that many shots on target.
"I am happy for two reasons. In the first half we played good football, we moved the ball around nicely and scored two very nice goals. Second half they didn't allow us to play, our full-backs couldn't come out with the ball so it was more of a battle.
"They became much more direct and hit a lot of long balls and I think we stood up to that very well so I am very happy about that.
"The team is getting better and better, more and more confident. so I hope we can go on like this but you never know because every game is a battle."