A detecting element for an inertial force sensor includes a mass section, an excitation section, and a detecting section. The excitation section excites the mass section along a third direction among a first direction, a second direction, and the third direction that are perpendicular to each other. The detecting section outputs a signal corresponding to displacement of the mass section along at least one of the first direction and the second direction. Resonance frequencies of the first direction and the second direction are set greater than a resonance frequency of the third direction.