Fuente: Wipo "Sensorization" A mounting structure of a liquid sensor comprising: a vibration cavity forming base portion which has a first surface and a second surface opposed to each other and in which a cavity for receiving a medium as a detection target is formed to be open toward the first surface side and a bottom surface of the cavity can vibrate; a sensor including a piezoelectric element having a first electrode formed on the second surface side of the vibration cavity forming base portion, a piezoelectric layer formed on the first electrode, and a second electrode formed on the piezoelectric layer; a mounting target member which is mounted with the sensor, the mounting target member having an upstream space which communicates with the cavity through an upstream flow path and a downstream space which communicates with the cavity through a downstream flow path; and an elastic seal member which is disposed between the sensor and the mounting target member and which seals a space between the sensor and the mounting target member.