A detecting device 100 detects an elastic wave propagating through the air. The detecting device 100 includes: a first electrode 12 that is a plate having a cantilever structure with a fixed end FX and a free end FR and that vibrates by being bent by the elastic wave; and a second electrode 32 that is a plate, that is opposed to the first electrode, and that has a predetermined distance from the first electrode. The detecting device 100 detects the elastic wave on the basis of a change in capacitance between the first electrode and the second electrode 32. An end of the second electrode 32 in a direction from the fixed end FX to the free end FR is closer to the fixed end than the free end.