The present invention provides a compound having a superior serotonin 5-HT2C receptor activating action.The present invention relates to a compound represented by the formula (1) wherein ring A is an aromatic carbocycle optionally having substituent(s) or an aromatic heterocycle optionally having substituent(s), X is —N(R1)—, —O— or the like, when ring A is an aromatic carbocycle optionally having substituent(s), then R1 is a hydrogen atom, an alkyl group optionally having substituent(s), or the like, and when ring A is an aromatic heterocycle optionally having substituent(s), then R1 is a hydrogen atom, an alkyl group optionally having substituent(s), a cycloalkyl group optionally having substituent(s), or the like, is a single bond or a double bond, and n is an integer of 0, 1 or 2, or a salt thereof.