To provide a composition exhibiting excellent controlling effects on plant diseases.

The plant disease control composition containing a pyridazine compound expressed by formula (I) (wherein, R1 indicates a chlorine atom, a bromine atom, a cyano group or a methyl group, and R2 indicates a hydrogen atom or a fluorine atom) and one or more kinds of carboxamide compound selected from the group (A) exhibits the excellent controlling effects on the plant diseases. The group (A) includes bixafen, isopyrazam, boscalid, fluopyram, fluxapyroxad, sedaxane, penflufen, flutolanil, mepronil, carboxin, thifluzamide, penthiopyrad and furametpyr.