A spiral-wound acid gas separation membrane element (1) includes a wound body which includes a laminate and a perforated core (5), the laminate being wound around the perforated core tube (5) and including: a separation membrane (2), a feed-side channel component (3), and an element constituent layer (e.g., permeate-side channel component (4)). The separation membrane (2) is provided with a sealing section (25) present at both widthwise ends of the separation membrane (2). The sealing section (25) is sealed with an adhesive. This makes it possible not only to separate acid gas from mixed gas more efficiently as compared to a conventional spiral-wound acid gas separation membrane element but also to save energy.