N-Arylphenylacetamide derivatives represented by the following formula [I]: ##STR00001## (wherein R.sup.1 is C.sub.1-6 alkoxy, etc.; R.sup.2 is hydrogen, --(CH.sub.2).sub.m--N(R.sup.6)(R.sup.7) (m is an integer of from 1 to 4; R.sup.6 is hydrogen, C.sub.1-4 alkyl, etc., R.sup.7 is hydrogen, etc.), etc.; R.sup.3 is hydrogen, halogen, etc.; R.sup.4 is C.sub.6-10 alkyl, --Y--R.sup.8 (Y is a single bond, C.sub.1-6 alkylene, C.sub.2-6 alkenylene, C.sub.2-6 alkynylene, etc., R.sup.8 is aryl, C.sub.3-8 cycloalkyl, C.sub.6-15 polycycloalkyl, etc.), etc.; R.sup.5 is hydrogen, etc.; and X.sup.1 is hydrogen), or pharmaceutically acceptable salts thereof or hydrates or solvates of the same, and a pharmaceutical composition containing the same. These compounds are useful as preventives and/or remedies giving no pain at the early stage of administration, which are efficacious in oral administration and have potent analgesic and antiinflammatory effects.