To provide a core stopper structure for an electronic clinical thermometer capable of pulling out a core for a predetermined distance and capable of preventing cutting of a lead wire.

A protruding stopper is provided on an inner wall of a body of the clinical thermometer equipped with a core having an electronic circuit and an electronic element in the body, and a protruding lock part is provided on a predetermined position of the core. When the core is pulled out of the body, the lock part of the core is locked with the stopper of the body, and the core is prevented from being pulled to the outer direction after the core is moved to the predetermined direction.