The inheritance of resistance to gall mite(Eriophys macrodonis) in boxthorn cultivars was studied with plants infected in open field. Segregation of the F$_1$ generation from crosses between resistant cultivars(Japan 1 and China 1) and susceptible line(CL42-56) hits a 3 resistant : 1 susceptible ratio, and the segregation ratio was 15 : 1 in cross between Japan 1 and China 1. It is concluded that gall mite resistance seemed to be controlled by two duplicate genes(El and E2), such that E1e1E2e2 symbolize the genotypes of China 1 and Japan 1. However, F, generation from Chungyanggugiza and CL42-56 cross did not showed clear segregation pattern but continuous variation was observed against gall mite resistance when resistance was determined on the basis of the percentage of galled leaves. Results indicated that the inheritance of resistance in Chungyanggugiza may be polygenic and complex. Also, Japan 1 and China 1 has a strong potential as a source of gall mite resistance, and Chungyanggugiza showing less resistance still has a valuable source.