The present invention provides isoxazole derivatives represented by the following formula (I): ##STR00001## (wherein R.sup.1 represents a hydrogen atom, C.sub.1-C.sub.20 hydrocarbon group or --C(.dbd.O)OR.sup.1a (wherein R.sup.1a represents a C.sub.1-C.sub.10 alkyl group, etc.); R.sup.2 and R.sup.3 represent a hydrogen atom, halogen atom, hydroxy group, C.sub.1-C.sub.20 alkyl group or C.sub.6-C.sub.20 aryl group, etc.; R.sup.4 represents a hydrogen atom, halogen atom, hydroxy group, cyano group, nitro group, amino group, C.sub.1-C.sub.20 hydrocarbon group, C.sub.1-C.sub.10 alkoxy group, C.sub.1-C.sub.10 acyl group, 5- to 7-membered heterocyclic group, etc.; R.sup.5 represents a hydrogen atom, halogen atom, hydroxy group, optionally substituted C.sub.1-C.sub.20 hydrocarbon group, C.sub.1-C.sub.20 alkoxy group, 5- to 7-membered heterocyclic group, etc.; and, n represents 0, 1, 2, 3 or 4), and a process of producing the same. The compounds are useful as intermediates for synthesis of pharmaceutical compounds, agricultural chemicals, dye compounds, etc. having the isoxazole skeleton.