The effects of the jasmonic acid derivative n-propyl dihydrojasmonate (PDJ) on ethylene signal transduction and endogenous jasmonic acid (JA) in apples infected with Botrytis cinerea (gray mold) were investigated. Apples were dipped into 400 μM PDJ solution and then inoculated with B. cinerea. The fruit were stored at 25 C and 95% relative humidity for 16 days after PDJ treatment. The inoculation without PDJ application (PDJ− Ino+) showed larger B. cinerea lesion diameters compared to the PDJ application with inoculation (PDJ+ Ino+) and the untreated controls. In contrast, the PDJ+ Ino+ group showed a higher ethylene production rate, higher 1-aminocyclo-propane-1-carboxylic acid (ACC) concentration, and greater expressions of ethylene-related genes [MdACS1 (ACC synthase), MdACO1 (ACC oxidase), MdETR1 (Ethylene receptor 1), MdERS1 (Ethylene response sensor 1), and MdCTR1 (Constitutive triple response 1)], and endogenous JA, MdAOS1 (Allene oxide synthase 1) gene. However, the abscisic acid concentrations were decreased in the PDJ+ Ino+ group. The results suggest that PDJ application induces ethylene production through ethylene-related genes and endogenous JA, resulting in B. cinerea infection inhibition.