Needle threader of sewing machine and sewing machine

1. A needle threader of a sewing machine, the needle threader comprising:

a needle bar supporter to which a needle bar holding a needle with a needle hole is attached;

a threader shaft supported in a movable manner in a vertical direction and in a rotatable manner;

a thread holding mechanism which is held by the threader shaft and which applies a tension to a thread so as to be substantially horizontal ahead of the needle hole; and

a threader mechanism which is held by the threader shaft and which comprises a hook that enters the needle hole upon a rotation of the threader shaft, wherein:

the hook comprises a capturing portion that captures the thread at a tip part of the capturing portion;

the capturing portion comprises a thread pathway where the thread enters or leaves, and a thread capturing space for capturing the thread; and

a width of a part where the thread pathway becomes the narrowest is formed so as to be narrower than a width of the thread capturing space, wherein

the thread enters the thread pathway in a tensioned condition, and

the width of the part where the thread pathway becomes the narrowest is formed so as to be narrower than an outer diameter of the thread not in a tensioned condition.

2. The needle threader according to claim 1 , wherein a convexity is provided in the thread pathway.

3. The needle threader according to claim 1 , wherein:

the hook has a tip formed in a hooky shape;

the thread pathway is formed at a basal part of the hooky shape and a tip part thereof; and

the convexity is provided at the basal part or the tip part.

4. The needle threader according to claim 2 , wherein:

the hook is provided in a movable manner in the vertical direction; and

the convexity has a tip part provided so as to be directed in a direction in which the hook moves.

5. The needle threader according to claim 2 , wherein the convexity is formed in a rounded shape.

6. A sewing machine comprising the needle threader of claim 1 .