Lower thread winding device

A lower thread winding device, comprising:

• a thread winding shaft to which a small-diameter bobbin and a large-diameter bobbin having a larger diameter than the small-diameter bobbin can be attached;
• a holder which is configured to be integrally rotated with the thread winding shaft, the holder being formed in a disk shape so that a plate thickness direction of the holder is directed in an axial direction of the thread winding shaft, the small-diameter bobbin or the large-diameter bobbin attached to the thread winding shaft being configured to be placed on the holder;
• an inner groove portion which is formed on the holder so as to be extended in an intersecting direction intersecting with a radial direction of the holder when viewed from the axial direction, one end portion of the inner groove portion being opened to one of the intersecting direction at an outer peripheral portion of the holder, another end portion of the inner groove portion being located at an inner side of the small-diameter bobbin attached to the thread winding shaft in the radial direction;
• an outer groove portion which is formed on the holder so as to be extended in the intersecting direction at an outer side of the inner groove portion in the radial direction of the holder, one end portion of the outer groove portion being curved toward the inner groove portion, communicated with the inner groove portion and located at the outer side of the large-diameter bobbin attached to the thread winding shaft in the radial direction, another end portion of the outer groove portion being located at the inner side of the large-diameter bobbin in the radial direction;
• a first blade portion provided on the holder so as to be exposed to the another end portion of the inner groove portion;
• and
• a second blade portion provided on the holder so as to be exposed to the another end portion of the outer groove portion.