The present invention provides a cytokine production inhibitor containing as an active ingredient an aniline derivative of the formula (I) or a salt thereof:
[wherein A is CO or SO2; Cy is an aryl group or a heterocyclic group; each of R1 and R2 which are independent of each other, is a halogen atom, a cyano group, a nitro group, an alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, a cycloalkyl group which may be substituted, a cycloalkenyl group which may be substituted, an aryl group which may be substituted, a heterocyclic group which may be substituted, an amino group which may be substituted or a —B-Q group; R3 is a -M1-M2-R5 group; R4 is a hydrogen atom or an alkyl group which may be substituted; x is an integer of from 0 to 5; y is an integer of from 0 to 4; and z is an integer of from 0 to 1].