Filament winding method and filament winding apparatus

A filament winding apparatus comprising:

• a bobbin rotation driving device, on which a bobbin, upon which filament is wound, is mounted, the bobbin rotation driving device driving and rotating the bobbin,
• a rotation angle detection device that detects a rotation angle of the bobbin rotation driving device,
• a dancer that oscillates in order to apply certain tension to the filament unwound from the bobbin,
• an oscillation angle detection device that detects an oscillation angle of the dancer, and
• a control device that is programmed to control the bobbin rotation driving device,
• wherein, when a new bobbin is mounted on the bobbin rotation driving device, the filament winding apparatus maintains a state where a distal end of the filament unwound through the dancer is fixed further beyond the dancer and the unwound filament is stretched, and
• the control device is programmed to rotate the bobbin and oscillate the dancer, and the control device is programmed to calculate a bobbin diameter of the bobbin mounted on the bobbin rotation driving device based on a rotation angle of the bobbin rotation driving device based on a detection signal from the rotation angle detection device, an oscillation angle of the dancer based on a detection signal from the oscillation angle detection device, and a length of the dancer.