To provide a diaphragm valve improved in sealability, which is used for a long time without damaging a diaphragm even after continuous opening and closing operations.

The diaphragm valve comprises: a valve body 1 having an inlet passage 3, an outlet passage 4, and a partition wall 5 which is located between both passages 3, 4 and curves the passages; a bonnet 15 mounted on the valve body 1; a compressor 14 which is supported by the bonnet 15 and is fixed to the lower end of a stem 18 to be engaged with a driving portion; and a diaphragm 9 which is fixed to the compressor 14, and is held between the valve body 1 and the bonnet 15, and has a line shape projecting portion 10 to be brought into pressure contact with the partition wall 5 and to be separated therefrom, and an annular projecting portion 11 to be brought into pressure contact with the portion around an opening portion 2 of the upper surface of the valve body 1 formed thereon. In this case, at least one projecting portion 12 having a width smaller than that of the line shape projecting portion 10 is provided on the line shape projecting portion 10.

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