Disclosed are: a compound represented by the general formula (I)； and others. (I) wherein A1 and A2 independently represent a nitrogen atom or a methine group which may be substituted； the ring B represents a 5- to 7-membered aliphatic ring or a spiro or bicyclo ring formed by the aliphatic ring and a 3- to 7-membered aliphatic ring which is different from the aforementioned aliphatic ring； R1 represents a hydrogen atom, a C1-C6 alkyl group which may be substituted or an aryl, aralkyl or heteroaryl group which may be substituted； R2 represents an aryl, aralkyl or heteroaryl group which may be substituted； and X represents a group represented by the formula =NH or =O. The compound has an excellent cell proliferation inhibition activity relying on a Wee1 kinase inhibition activity and an additive/synergistic effect with other anti-cancer agent, and is therefore useful in the medical field.
