Abstract: The present invention discloses an automatic ink supply device comprising: a main body installed in the one side of a printer, including a bottom supporting plate and a top supporting plate of a predetermined height with multiple supporting holes in the inside of the main body; multiple bottom tanks supported in stable in the state of penetrating the corresponding supporting holes of the bottom supporting plate, including a close cap in the top side, including a hose hole in the center of the close cap, including a nozzle hose from the inner bottom side of the close cap to the outside of the main body, and including a nozzle in the end of the corresponding nozzle hose connected to the printer, respectively; and multiple top tanks supplied by ink with different colors from one another in the state of penetrating the supporting holes of the top supporting plate, including a supply hose with an O/C (open/close) valve in the bottom side, maintaining an amount of charged ink constantly in the corresponding bottom