To provide a sensitive sensor and a sensitive instrument capable of sensing a plurality of kinds of objects.

A first vibration mode is excited by connection of a first electrode pair 51 and a second electrode pair 52 formed on a quartz piece 31, to a first oscillation circuit 71, and a second vibration mode is excited by connection of them to a second oscillation circuit 72. A first reaction film 61 which reacts to a first object but does not react to a second object is formed in a region corresponding to a node of the second vibration mode in a vibration region, so that the first object can be sensed by excitation of the first vibration mode. A second reaction film 62 which reacts to the second object but does not react to the first object is formed in a region corresponding to an antinode of the second vibration mode in the vibration region, so that the second object can be sensed by excitation of the second vibration mode.