The present invention provides a live fish keeping device (10) for a fishing cooler which allows a user to fill a fishing cooler (1) with water and keep and carry fish alive for a long period of time. In regards to the fishing cooler (1) comprising a main body (2), a cover (3) and a stopper (5) airtightly screw-joined to an outlet (4) of the main body (2), the live fish keeping device (10) for a fishing cooler of the present invention comprises a bubble generator (11) coupled to one side of the main body (2) to be detached； an air supply hose (13) connected to the bubble generator (11) and installed on the outlet (4) of the main body (2) to allow air including oxygen to be supplied； and an air circulation cap (12) having an air discharge hose (14) installed thereon, wherein the air discharge hose (14) is fixed in the main body (2) to allow the air in the main body (2) to be discharged to the outside, and being screw-joined to the outlet (4) in replacement of the stopper (5) of the outlet (4). The present invention provides multiple effects of allowing the fishing cooler (1) to have a cooler and a maintenance container simultaneously, wherein the cooler allows the freshness of fish to be maintained for a long period of time by putting ices, dry ice, etc. into the cooler and the maintenance container allows fish to be kept and carried alive for a long period of time by putting water into the maintenance container； allowing the fishing cooler (1) and the maintenance container to be compatibly used only by the replacement of the stopper (5) by the air circulation cap (12), thereby enhancing convenience for use； enhancing cold insulation ability by increasing heat insulation efficiency as a separate hole or the like is not formed on the main body (2) when the fishing cooler (1) is used as the cooler； preventing the water in the main body (2) from being leaked when the fishing cooler (1) is used as the maintenance container, etc.본 발명은 낚시쿨러(1)에 물을 채우고 물고기를 활어상태로 장기간 보관 및 운
