A transition metal complex represented by the formula (1): ##STR00001## wherein M is a Group 4 transition metal, A is a Group 16 element, B is a Group 14 element, n is an integer of 0 or 1, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be the same or different and each independently denotes a substituent selected from the group consisting of the groups (I) and (II): group (I): hydrogen, alkyl and so on, group (II): alkoxy, alkylthio and so on, provided that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is a substituent selected from group (II); R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10, X.sup.1 and X.sup.2 may be the same or different and are each hydrogen, halogen, alkyd or the like; and a catalyst for olefin polymerization comprising said complex, an organoaluminum compound and a boron compound are provided.