A fluid handling device has a first substrate, a second substrate, and a resin film disposed between the first substrate and the second substrate. The first substrate includes a first channel, a valve body facing area having a substantially circular segment-shaped opening, a second channel, and a partition wall formed between the valve body facing area and an end on one side of the second channel. The second substrate includes a pressure chamber. The resin film includes a substantially spherical cap-shaped diaphragm portion. A radius of an outer edge of the diaphragm portion is smaller than a radius of a circular arc of the valve body facing area. The diaphragm portion is so arranged as to straddle the valve body facing area and the end on one side of the second channel.