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; andR5 is group represented bywherein R6 and R7 are each independently hydrogen or organic group;XA and XB are each independently bond, lower alkylene, etc.