A collision avoidance assistance device for a vehicle, the collision avoidance assistance device comprising: a capturing unit configured to acquire an image of at least part of the surroundings of the vehicle; an animal image detection unit configured to detect the presence or absence of an image of a tetrapod animal in the image; an animal type determination unit configured to determine a type of the tetrapod animal when the image of the tetrapod animal is detected in the image; an animal presence area prediction unit configured to predict a future area in which the tetrapod animal will be present, based on behavior characteristics index values representing behavior characteristics of the determined type of the tetrapod animal, wherein the animal presence area prediction unit calculates a probability Pa of the predicted future area of the tetrapod animal; a vehicle presence area prediction unit configured to predict the future area in which the vehicle will be present and calculate a probability Pv of the predicted future area of the vehicle; a collision possibility determination unit configured to determine a probability Pc of collision of the animal with the vehicle if the predicted future area of the tetrapod animal and the predicted future area of the vehicle are within a predetermined distance L, wherein the probability Pc of collision is calculated by multiplying the probability Pa of the predicted future area of the tetrapod animal by the probability Pv of the predicted future area of the vehicle; and an assistance processing performing unit configured to perform assistance processing for collision avoidance when it is determined that the probability Pc of collision of the tetrapod animal with the vehicle is higher than a predetermined value Pco. a capturing unit configured to acquire an image of at least part of the surroundings of the vehicle; an animal image detection unit configured to detect the presence or absence of an image of a tetrapod animal in the image; an animal type determination unit configured to determine a type of the tetrapod animal when the image of the tetrapod animal is detected in the image; an animal presence area prediction unit configured to predict a future area in which the tetrapod animal will be present, based on behavior characteristics index values representing behavior characteristics of the determined type of the tetrapod animal, wherein the animal presence area prediction unit calculates a probability Pa of the predicted future area of the tetrapod animal; a vehicle presence area prediction unit configured to predict the future area in which the vehicle will be present and calculate a probability Pv of the predicted future area of the vehicle; a collision possibility determination unit configured to determine a probability Pc of collision of the animal with the vehicle if the predicted future area of the tetrapod animal and the predicted future area of the vehicle are within a predetermined distance L, wherein the probability Pc of collision is calculated by multiplying the probability Pa of the predicted future area of the tetrapod animal by the probability Pv of the predicted future area of the vehicle; and an assistance processing performing unit configured to perform assistance processing for collision avoidance when it is determined that the probability Pc of collision of the tetrapod animal with the vehicle is higher than a predetermined value Pco.