An ink supply apparatus includes an ink filling port, an ink storage section, an ink flow path, a displacement section, an ink supply port, and a sealing structure. The ink storage section is communicated with the ink filling port to store the ink. The ink flow path is communicated with the ink storage section. The displacement section defines a portion of the ink flow path, and configured and arranged to be displaced according to internal pressure in the ink flow path so as to be detected by the printer. The ink supply port is communicated with the ink flow path to supply the ink from the ink flow path to the printer. The sealing structure seals an inner section of the ink flow path at least in a low ink remaining amount state where a remaining amount of the ink is a predetermined amount or less.