A QCM sensor for detecting a physical quantity of a sample includes a quartz crystal vibrator for measurement, a quartz crystal vibrator for reference, and a housing accommodating the quartz crystal vibrator for measurement and the quartz crystal vibrator for reference. The quartz crystal vibrator for measurement has a first electrode that is contacted by a measurement sample to be detected, and a first quartz substrate provided with a surface on which the first electrode is formed. The quartz crystal vibrator for reference has a second electrode that is contacted by a reference sample as a reference when detecting a physical quantity of the measurement sample, and a second quartz substrate provided with a surface on which the second electrode is formed. A confining portion connects to the housing to confine the reference sample in a state of contacting the second electrode.