Metal enrichment of intracluster medium (ICM) is reanalysed in the hierarchical galaxy formation scenario. In order to investigate metal abundances of $\alpha$ and iron-peak elements, we incorporate metal production processes by type Ia supernovae (SNe Ia) as well as type II supernovae (SNe II) into the GALFORM model of semi-analytic galaxy formation. We find that a top-heavy initial mass function (IMF) of stars with a power index $x\simeq 0.35$ for starburst is required under the constraint that the IMF for quiescent disc star formation is the Kennicutt IMF. Our model shows an only mild evolution of [Fe/H] as suggested by a recent observation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html