PROBLEM TO BE SOLVED: To enable an opening direction of a collateral to be detected with a high degree of accuracy by reducing unsteadiness of a measuring electrode.SOLUTION: A canal instrument holder is provided for locking a measuring electrode to be inserted into a dental root canal in dental diagnosis. The canal instrument holder comprises: an insulating tube that extends in one direction； a conductor stick that has a conductor hook and is inserted into the insulating tube with the conductor hook left outside a tip opening part of the insulating tube； an operation part that is connected to the insulating tube and presses a rear end of the conductor stick so as to project the conductor hook from the tip opening part； and an energization part that energizes the conductor stick to the rear end side so as to draw back the conductor hook after the operation by the operation part and lock the measuring electrode in the opening part. In the state of locking the measuring electrode, total length of the insulating tube and the operation part is set within a range from 35 mm to 55 mm.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2019,JPO&INPIT
