Provided is a pharmaceutical composition comprising a Cdc7 inhibitor and an M phase promoter. In particular, the Cdc7 inhibitor contained in the pharmaceutical composition is a furanone derivative represented by formula (I), or a pharmaceutically acceptable salt thereof. (In the formula, A is -COOR1 or a hydrogen atom R1 is a hydrogen atom, an optionally substituted hydrocarbon group, or an optionally substituted heterocycle R2 and R3 are the same or different and are each a hydrogen atom, an optionally substituted hydrocarbon group, an optionally substituted phenyl group, an optionally substituted heterocycle, an optionally substituted heterocyclic condensed ring, or an optionally substituted amino group. Alternatively, R2 and R3 may, together with the nitrogen atoms bonding the same, form an optionally substituted heterocycle or optionally substituted heterocyclic condensed ring. R4 is a hydrogen atom or halogen atom. However, if A is -COOR1, R2 and R3 are not both simultaneously optionally substituted amino groups. When A is a hydrogen atom, R3 is a hydrogen atom.)
