1. A sensing sensor for detecting a density of a sensing object in a sample solution as a frequency variation of a piezoelectric resonator, the sensing sensor comprising:a main body portion that includes a supply region to which the sample solution is supplied;
the piezoelectric resonator disposed to face the supply region, the piezoelectric resonator including a capturing layer that captures the sensing object;
a connecting terminal configured to attachably/detachably connect a conductive path connected to an electrode of the piezoelectric resonator to a frequency measuring unit; and
an information storage that stores calibration curve information to specify a calibration curve that indicates a relationship between a density of the sensing object and a frequency variation amount of the piezoelectric resonator before and after supplying the sample solution.