Disclosed herein are an apparatus and method for preventing a collision between vessels. The apparatus includes a position information processing unit, an expected collision route calculation unit, an escape route calculation unit, and a control unit. The position information processing unit collects information about the position of a reference vessel using a mobile terminal and receives information about a counterpart vessel from a user. The expected collision route calculation unit calculates an expected collision route based on the information. The escape route calculation unit calculates escape routes if the possibility of a collision is above a set value. The control unit provides the escape routes, compares changes in actually measured positions of the vessels with the escape routes, and manages navigation on the results of the comparison between changes in the actually measured positions of the vessels and the escape routes.