"It is mixed feelings," Martinez told BBC Sport. "Relief but frustration as well because that was an incredible chance for us to win away from home but we couldn't get it and that is frustrating.
"We couldn't take advantage of the man advantage and that is frustrating. We are a better side than that. We were cagey.
"We didn't use our advantage well enough. We allowed QPR to be very effective with their defending. It is disappointing to concede a goal in open play in the manner the game was going."
The draw has seen Wigan slip into the relegation zone on goal difference with seven games left to play.