Ink jet black ink, ink set, ink jet recording method, ink cartridge, recording unit and ink jet recording apparatus

An ink jet black ink comprising at least a compound represented by the following general formula (I) or a salt thereof, characterized in that

• the ink jet black ink further comprises at least one moisture-retaining nitrogen compound, and
• the pH of the ink and the pH of the ink after storing for 10 days in an environment at a temperature of 60° C. are 9.0 or less:
• wherein R1, R2, R3 and R4 represent each independently a hydrogen atom;
• a hydroxyl group;
• an amino group;
• a carboxyl group;
• a sulfonic group;
• an alkyl group having 1 to 4 carbon atoms;
• an alkoxy group having 1 to 4 carbon atoms;
• an alkoxy group substituted with a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic group or a carboxyl group;
• an alkoxy group having 1 to 4 carbon atoms which may be further substituted with a carboxyl group or a sulfonic group;
• or an amino group substituted with a phenyl group, an alkyl group or an acyl group, and n represents 0 or 1.