A fluid handling device, comprising: a substrate including a first channel, a second channel and a partition wall formed between the first channel and the second channel; a film including a diaphragm, the film being disposed on the substrate so that the diaphragm faces the partition wall; and a sliding member slidable on the film while contacting with the film, the sliding member including a protrusion formed on an underside thereof, and the sliding member being disposed on the film with the underside facing the film, wherein: the sliding member is capable of switching between a first state and a second state by sliding on the film, wherein the protrusion is positioned so as not to face the partition wall with the diaphragm therebetween in the first state, and the protrusion is positioned so as to face the partition wall with the diaphragm therebetween in the second state.