Provided are a nitrogen-containing aromatic compound useful for an organic electroluminescent device, and an organic electroluminescent device (organic EL device) that improves luminous efficiency of the device and sufficiently ensures driving stability of the device. The nitrogen-containing aromatic heterocyclic compound is represented by the following formula (1). The organic EL device includes an organic layer that contains the nitrogen-containing aromatic heterocyclic compound between an anode and a cathode laminated on a substrate. In the formula (1), a ring A represents an aromatic ring represented by the formula (1a) and fused with two adjacent rings, a ring B represents a heterocycle represented by the formula (1b) and fused with two adjacent rings, Y's each represent C—R or N, X's each represent N—Z, O, S, or Se, R represents hydrogen, an alkyl group, an aromatic group, or the like, and Z represents an alkyl group, an aromatic group, or the like.