An object of the present invention is to provide a spiral membrane element that can improve the barrier property of a fiber reinforced plastic layer having a fiber roll as a reinforcing phase and that can effectively prevent occurrence of cracks. The spiral membrane element of the present invention is a spiral membrane element containing a cylindrical roll R in which a separation membrane, a feed-side flow passageway member, and a permeate-side flow passageway member are spirally wound in a laminate state around a perforated center tube 5 and in which a sealing part for preventing mixing of feed-side fluid and permeate-side fluid is disposed, wherein a fiber reinforced plastic layer 26 having a fiber roll as a reinforcing phase is formed on the outer circumferential side of said cylindrical roll R, and a plastic layer 24 is disposed in the inner part or on the inner side of the fiber reinforced plastic layer 26 approximately over the entire length and approximately over the entire circumference of the fiber reinforced plastic layer 26.