A composite synthetic resin material forming apparatus comprises an outer channel having an outer outlet, an inner channel having an inner outlet opening into the outer channel, outer synthetic resin supply means for flowing an outer synthetic resin through the outer channel, and inner synthetic resin supply means for flowing an inner synthetic resin through the inner channel. Opening and closing means for selectively opening and closing the inner outlet is disposed. The outer synthetic resin supply means intermittently supplies the outer synthetic resin to the outer channel in accordance with opening and closing of the inner outlet by the opening and closing means.