| 摘要 |
A separation membrane element including: a perforated water collection tube; and an envelope-shaped membrane which is formed of a separation membrane and is wound around a periphery of the perforated water collection tube, in which the separation membrane has a difference in surface level of 100 to 2,000 �m on at least one surface thereof and has a strip-form region in each of both ends of the separation membrane in terms of the longitudinal direction of the perforated water collection tube, the strip-form region having an average difference in surface level of 50 �m or less. |
