Ancelotti insists mistakes have only arisen because the Czech international is so keen to dominate his penalty area.
The Blues boss said: "Cech is one of the most important players for this team, one of the best goalkeepers in the world. I like him because he takes on responsibility in the box, he likes to come out to catch the ball.
"Above all, that's important in England, to have this kind of goalkeeper.
"A goalkeeper that takes responsibility can make the odd mistake.
"I prefer to have a goalkeeper who takes responsibility than one who just stays on his goalline and doesn't take that responsibility."