Abstract: A synthetic resin tube comprises an internal layer which is made of non-rigid synthetic resin and has a substantially smooth inner circumferential surface, and an external layer which is formed by winding a strip made of rigid synthetic resin around an outer circumferential surface of the internal layer overlapping winds of the strip and connecting the external layer with the internal layer, a cross section of the strip being S-shaped. When the external layer is formed, adjacent winds of the strip are connected temporarily and capable of being disconnected. After the external layer is formed, flexibility can be given to an optional length of the tube by removing the temporary connection among the winds of the strip.