A method for sequestrating carbon dioxide in the ocean of the present invention coverts carbon dioxide into a high concentration of bicarbonate ions by using a neutralization method using calcium oxide commonly contained in alkaline industrial waste, prepares elution water for stably containing bicarbonate ions even when making contact with the atmosphere through aeration, and discharges the elution water into an area of the ocean of a relatively shallow depth to sequestrate carbon dioxide. According to the present invention, the present invention is a carbon dioxide storage method which uses alkaline industrial waste to carry out carbon dioxide ocean sequestration at relatively low cost, and can sequestrate carbon dioxide for a long time while minimizing bad environmental influences such as ocean acidification and the like, and is thus environmentally friendly. Therefore, it is possible to actively respond to carbon dioxide emission restrictions and simultaneously achieve economical efficiency by securing certified emission reductions henceforth.