An azole derivative according to the invention is represented by Formula (I), wherein each of Ra and Rb denotes a hydrogen atom, or a C1-C6 alkyl group, a C2-C6 alkenyl group or a C2-C6 alkynyl group; Ra and Rb may be substituted with Xa or Xb which is a halogen atom; each of na and nb denotes 0 or the number of Xa- or Xb-substituted hydrogen atoms among the hydrogen atoms in Ra or Rb; each Y denotes a halogen atom, a C1-C4 alkyl group, a C1-C4 haloalkyl group, a C1-C4 alkoxy group, a C1-C4 haloalkoxy group, a phenyl group, a cyano group or a nitro group; m denotes 0 to 5; and A denotes a nitrogen atom or a methyne group. As a result, an azole derivative contained as an active ingredient in an agro-horticultural agent having an excellent controlling effect on diseases can be provided.