A liquid specimen sensor, comprising: a sensor substrate on an upper surface of which a flow path is located; and a sensor chip comprising a piezoelectric substrate located on the sensor substrate, and a pair of first IDT electrodes and a pair of second IDT electrodes located on an upper surface of the piezoelectric substrate and located in the flow path; a pair of first input conductors connected to one of the pair of first IDT electrodes and extending to an outside of the flow path; a pair of first output conductors connected to the other of the pair of first IDT electrodes and extending to the outside of the flow path; a pair of second input conductors connected to one of the pair of second IDT electrodes and extending to the outside of the flow path; and a pair of second output conductors connected to the other of the pair of second IDT electrodes and extending to the outside of the flow path, wherein each of the eight conductors of the pair of first input conductors, the pair of first output conductors, the pair of second input conductors, and the pair of second output conductors includes a bonding wire which extends from an upper surface of the sensor chip to the upper surface of the sensor substrate and is wholly located in the flow path, such that the upper surface of the sensor chip, the bonding wire, and the upper surface of the sensor substrate contact the liquid specimen flowing in the flow path, and the sum of line lengths in the flow path of the pair of first input conductors and the pair of first output conductors and the sum of line lengths in the flow path of the pair of second input conductors and the pair of second output conductors are equal. a sensor substrate on an upper surface of which a flow path is located; and a sensor chip comprising a piezoelectric substrate located on the sensor substrate, and a pair of first IDT electrodes and a pair of second IDT electrodes located on an upper surface of the piezoelectric substrate and located in the flow path; a pair of first input conductors connected to one of the pair of first IDT electrodes and extending to an outside of the flow path; a pair of first output conductors connected to the other of the pair of first IDT electrodes and extending to the outside of the flow path; a pair of second input conductors connected to one of the pair of second IDT electrodes and extending to the outside of the flow path; and a pair of second output conductors connected to the other of the pair of second IDT electrodes and extending to the outside of the flow path, wherein each of the eight conductors of the pair of first input conductors, the pair of first output conductors, the pair of second input conductors, and the pair of second output conductors includes a bonding wire which extends from an upper surface of the sensor chip to the upper surface of the sensor substrate and is wholly located in the flow path, such that the upper surface of the sensor chip, the bonding wire, and the upper surface of the sensor substrate contact the liquid specimen flowing in the flow path, and the sum of line lengths in the flow path of the pair of first input conductors and the pair of first output conductors and the sum of line lengths in the flow path of the pair of second input conductors and the pair of second output conductors are equal.