The present invention provides a novel benzodiazepine compound that blocks the IKur current or the Kv1.5 channel potently and more selectively than other K+ channels. The benzodiazepine compound of the invention is represented by General Formula (1) wherein R1, R2, R3, and R4 are each independently hydrogen or lower alkyl； R2 and R3 may be linked to form lower alkylene； A1 is lower alkylene optionally substituted with one or more hydroxy； and R5 is group represented by wherein R6 and R7 are each independently hydrogen or organic group； XA and XB are each independently bond, lower alkylene, etc.
