PURPOSE: To measure components in the body liquid quickly by connecting an injection section for injecting a body liquid to be tested into fluid buffer liquids, a mixer for mixing the liquids, a flow cell with an enzyme electrode and a drain section with a line pipe.

CONSTITUTION: A buffer liquid at a buffer storage section A is sucked up with a pump 6, fed to a measuring line X and raised up to a measuring temperature with an incubation coil 1. The buffer liquid of a specified temperature reaches a sample port 2 and a sample body liquid is injected into the fluidizing buffer liquid. After mixed thoroughly with a mixer 3, the fluid buffer liquid receiving the sample is fed to a flow cell 5 with an enzyme electrode 4 to measure a specification concentration in the sample body liquid. The mixture liquid measured is discharged from a drain line Z through a 3-way cock 7.