A composition for controlling plant diseases comprising a tetrazolinone compound represented by a formula (1):wherein n is an integer of any one of 0 to 5； R1 represents a halogen atom and the like； R2 represents a C1-C3 alkyl group and the like； the R1 or R2 can have independently halogen atom(s) in the alkyl moiety； with the proviso that when n is an integer of 2 or more, two or more of the R1 may be different from each other, and an QoI compound, preferably the composition for controlling plant diseases wherein a weight ratio of the tetrazolinone compound to the QoI compound is that of the tetrazolinone compound/the QoI compound=0.1/1 to 10/1, shows an excellent controlling efficacy on plant diseases.
