Impregnated flat membrane element and manufacturing method thereof

Provided are an immersed flat membrane element and a method for manufacturing the same, in which the peel strength and cross-sectional profile of a single water stop section formed by joining a separation membrane to the peripheral section of a filter plate are designed, and the separation membrane can be prevented from being broken when only the water-permeable section side of the water stop section is partially peeled off, the filtration performance can be maintained for a long period of time, and the service life can be prolonged. And the service life can be prolonged by repairing the stripping of the permeable part side of the water stop part. An immersion type flat membrane element in which a water stop section is formed by joining a separation membrane along the entire circumference of a peripheral section of a resin filter plate, characterized in that the water stop section is configured from continuous lines having a single concave cross-section, and the peel strength of a weld site (1) forming a shou