To provide a spool for machine-sewing thread, which is storable with a bobbin installed on top of the spool, so that labor of looking for a bobbin and a spool having thread of the same color and the same kind is eliminated, and that they can be stored in order.

On a head part of the spool 1 for machine-sewing thread, a plurality of claws for mounting a bobbin with the tip bent inward is provided to fit the outer circumference of a bottom surface part of the bobbin 3. By fitting and installing the bottom surface part of the bobbin 3 between the claws 2 for installing the bobbin, the spool 1 for machine-sewing thread is attachable with the bobbin 3 to be stored together. Also, since a cap 7 provided with the claws for installing the bobbin is mounted on a conventional spool for machine-sewing thread, the bobbin 3 can be installed on the conventional spool for machine-sewing thread.