Sulfonamide derivative or a pharmaceutically acceptable acid addition salt thereof

The present invention aims at providing a novel low-molecular compounds exhibiting orexin receptor agonistic activity are expected to be useful as a prophylactic or therapeutic agent such as narcolepsy. The present invention relates to compounds of the general formula (I) compound or a pharmaceutically acceptable acid addition salt represented by :( symbols are the same meaning as defined in the specification of formula) with orexin receptor agonist activity , and it provides the compound or orexin receptor agonist containing a pharmaceutically acceptable acid addition salts.