To provide a method of laying the multiple lines of subaqueous cables across a river and the like simultaneously, that enables the multiple lines of the subaqueous cables to be laid simultaneously and thereby makes it possible to shorten the laying work period and to reduce the cost of the laying work.

The multiple lines of the subaqueous cables, extended from a plurality of cable extending-out drums on which the subaqueous cable is wound, installed on an extending-out land part toward the opposite side land part, are stored and bundled with multiple pieces of connected floating members. The top end parts of the extending-out side of the multiple lines of the subaqueous cables are gathered into a top-end integrating part, to which a leading wire is fixed. Then, the leading wire is pulled by a winch installed at the opposite land part, so that the multiple lines of cables can be laid by subsequently cutting off the cables of the multiple pieces of the connected floating members, that reach the laying position and by laying the cables on the river bed.