An image storage apparatus comprises an image capture unit configured to sequentially capture images of a subject, a storage unit including storage areas to store the images of the subject captured by the image capture unit, a storage controller configured to overwrite a storage area which is permitted to be overwritten with an image of the subject captured by the image capture unit, a life setting unit configured to set a life of the storage area which is overwritten by the storage controller, a life controller configured to change gradually the life of the storage area set by the life setting unit, a determination unit configured to determine whether the life of the storage area changed by the life controller expires or not, and a permission unit configured to permit to overwrite a storage area when the determination unit determines that the life of the storage area expires.