A detection sensor (10) includes: plural beam-like resonators (30A, 30B), a vibration characteristic of which changes according to adsorption or sticking of a substance having a mass and one end of each of which is fixed; a driving unit (40) that vibrates the resonators; and a detecting unit (40) that detects a change in the vibration in the resonators to detect the substance. The plural resonators have lengths different from one another. When the length of an arbitrary resonator is represented as L, a difference ΔL between the length L and the length of the other resonators is set to satisfy the following condition: 2(ΔL/L)>1/Q (Q represents a Q factor of the resonators). The driving unit vibrates the respective plural resonators at frequencies corresponding to resonant frequencies of the resonators.