To provide a constitution capable of reducing a tension variation in yarn unreeled to the downstream side from a yarn storage roller in a yarn storage device.

The yarn storage device 12 includes the yarn storage roller 21 capable of winding spinning yarn 10, and a downstream side guide 26. A guide groove 91 possessed by the downstream side guide 26 converges a yarn guide of the spinning yarn 10 from the yarn storage roller 21 on a point on the rotational axis 92 of the yarn storage roller 21. A downstream yarn guide 94 being the yarn guide passed through the guide groove 91 extends while inclining to the rotational axis 92. A case of projecting a conical surface being a locus of the yarn guide between the yarn storage roller 21 and the guide groove 91 and the downstream yarn guide 94 on a vertical virtual plane including the rotational axis 92 is supposed. In a triangle formed on the virtual plane by the conical surface, angles P and Q formed by respective two sides 96 and 97 sandwiching the rotational axis 92 and a straight line formed on the virtual plane by the downstream yarn guide 94, are 90 degrees or more in both.