There are provided a therapeutic preparation for anxiety neurosis or depression which comprises a MC₄ receptor antagonist as an effective ingredient; and a piperazine derivative represented by Formula [1]: ##STR1##

[wherein Ar¹ is a phenyl group, a substituted phenyl group, a naphthyl group or a substituted naphthyl group; Ar² is a naphthyl group, a substituted naphthyl group, a quinolyl group, a group represented by the formula: ##STR2##

(wherein R⁴ is a hydrogen atom or a halogen atom; and X—Y is CH—NH, CH—O, CH—S or N—O) or a group represented by the formula: ##STR3##

(wherein R⁵ is a hydrogen atom, a hydroxyl group or a C_1-10 alkoxy group); R¹ is a hydrogen atom, a C_1-10 alkyl group, a C_3-8 cycloalkyl group, a C_3-10 alkenyl group, a phenyl group, a 1-cyanoethyl group, a pyrimidin-2-yl group or an amidyl group; R² and R³ are the same or different, and are each a hydrogen atom or a C_1-10 alkyl group; A-B is N—CH₂, CH—CH₂, C(OH)—CH₂ or CCH; T¹ is a single bond, —N(R⁶)— (wherein R⁶ is a hydrogen atom or a C_1-10 alkyl group), —O—, —CHCH— or —C(O)—; n is an integer of from 1 to 10 and when T¹ is a single bond, —CHCH— or —C(O)—, n is an integer of from 2 to 10 when T¹ is —N(R⁶)— or —O—], or a pharmaceutically acceptable salt thereof.