This liquid sample measurement device is provided with: a lancet mounting part to and from which a lancet device having a skin contact section for puncturing skin can be attached and detached; a sensor mounting part to which a biosensor, which is spotted with blood that comes out from the punctured skin, can be attached; and a measurement part that uses the biosensor attached to the sensor mounting part to measure the amounts of substances in the blood. The liquid sample measurement device includes a feature that makes it necessary to replace a lancet device that has been attached to the lance mounting part and has punctured skin, each time a lancet device is used to puncture skin.