We present a result of age estimation for star clusters in M33 .
We obtain color-magnitude diagrams ( CMDs ) of resolved stars in 242 star clusters from the HST/WFPC2 images .
We estimate ages of 100 star clusters among these , by fitting the Padova theoretical isochrones to the observational CMDs .
Age distribution of the star clusters shows a dominant peak at log ( t ) \sim 7.8 .
Majority of star clusters are younger than log ( t ) = 9.0 , while ten star clusters are older than log ( t ) \sim 9.0 .
There are few clusters younger than log ( t ) = 7 in this study , which is in contrast with the results based on the integrated photometry of star clusters in the previous studies .
Radial distribution of the cluster ages shows that young to intermediate-age clusters are found from the center to the outer region , while old clusters are distributed farther from M33 center .
We discuss briefly the implication of the results with regard to the formation of M33 cluster system .