The present invention provides a compound having a superior serotonin 5-HT 2C receptor activating action, which is represented by the formula wherein A is -OR 1 or -S(O) p R 2 , R 1 and R 2 are the same or different and each is a hydrogen atom, a hydrocarbon group optionally having substituent(s), or a heterocyclic group optionally having substituent(s), and p is 0, 1 or 2, or a salt thereof.