PURPOSE: To measure the titled activity rapidly and precisely, by feeding a test specimen solution, a substrate solution for measuring GOT, etc. to a cell provided with an enzyme electrode having an immobilized oxygen membrane of L-glutamate oxidase, and measuring electrode output.

CONSTITUTION: The cell 3 is equipped with the enzyme electrode 5 provided with the immobilized enzyme membrane 4 obtained by immobilizing L-glutamate oxidase on a porous high polymer carrier. The cell 3 is charged with the buffer solution 15, the test specimen solution 1, and the substrate solution for measuring glutamic-oxaloacetic transminase (GOT) or glutamic-pyruvic transaminase (GPT) 14 to carry out a reaction. Then, formed L-glutamic acid is reacted with L- glutamate oxidase, evolved hydrogen peroxide or reduced enzyme is detected by the electrode 5, recorded by the recorder 7, so that GOT activity or GPT activity in the test specimen solution 1 is measured.