The present invention provides a method for manufacturing a fish stock for cooking a fish using cordyceps militaris and hovenia dulcis, a fish stock manufactured by the same, and a method for cooking codfish stew soup using the same, capable of removing or reducing toxic or harmful ingredients and increasing an effective ingredient of a minor ingredient comprising the cordyceps militaris and the hovenia dulcis when cooking the soup or boiled food using the fish. To achieve the purpose of the present invention, according to the present invention, the method for manufacturing a fish stock for cooking a fish using cordyceps militaris and hovenia dulcis includes: a step of manufacturing a first preliminary stock by putting radish, onion, kelp, a spring onion root, chili pepper seeds, laurel, anchovies, a dried pollack head, dried pollack skin, and water into a first heating container and cooling the same to the room temperature after individually heating the same for predetermined first cooking time and for predetermined second cooking time by strong fire and middle fire in order； a step of manufacturing a second preliminary stock； a step of manufacturing a third preliminary stock by repeatedly heating a third heating container by the middle fire two or three times after putting the hovenia dulcis which is cut in advance and the predetermined water into the third heating container and by cooling the third heating container to the room temperature； and a step of mixing the first to third preliminary stock in a predetermined mixing ratio. The step of manufacturing the second preliminary stock includes: a step of drying the cordyceps militaris for a predetermined drying time at a predetermined temperature after spraying a predetermined amount of alcohol to the dried cordyceps militaris, and firstly heating the water in a second heating container until the water is reduced to 45-55% after putting the dried cordyceps militaris, jujube, and the water into the second heating c
