To provide a jib sail for facilitating replacement of sail.

This jib sail such as a stream jib sail SJ includes an enclosing part 1 for enclosing a jib furring device FG or a fore stay from the outside, and a pair of sail parts 2, 2 formed to be connected to both sides of the enclosing part 1 and having a head 2a, a tack 2b and clew 2c to be used in an overlap state. In order to set the stream jib sail SJ, the enclosing part 1 is placed on the outside of the jib furring device FG, a first fitting parts A, A of one pair of sail parts 2, 2 are collectively fixed to the hull H side, and second fitting parts B are collectively fitted to a jib halliard. Third fitting parts C are collectively fitted to a jib seat. One sail part forms the front of the storm jib sale SJ and the other sail part 2 forms the back.