The authors have estimated the age of the open cluster NGC 2287 (M41) by taking into account the rotation of the member stars. Having obtained the theoretical Hertzsprung-Russell diagram from observed colour-magnitude diagram, they have discussed two methods, given in the literature, to estimate the age of the cluster. The first method is to determine the turn-off point on the cluster Main-Sequence. It gives an age of 3.10×107yr. The other is fitting the position of the red giants with the evolutionary tracks of rotating stars with different masses on the H-R diagram. Herewith an age of about 8.00×107yr has been inferred.