PROBE

PROBLEM TO BE SOLVED: To accurately execute an accurate measuring by a method wherein a probe is directly inserted into a throughhole without carrying out a complicated work in which a check pin is provided to be erectingtly fixed to the throughhole placed in a printed circuit board when checking of conductivity or measuring of a characteristic for a circuit on the board is executed. SOLUTION: This probe comprises a plurality of connection pieces 20 which are supported so as to be movable back and force in an inner/outer diameter direction in a condition wherein they are urged in an inner diameter direction by a tip section of a holding section 12, a cone-shaped expansion piece 18 which is fixed to a tip section of a connection member 17 penetrating a hollow formed by the plurality of connection pieces, a spring 16 that connects the connection member 17 with an operation member and a U-shaped slit 25 which is formed on the wall of the holding section by the penetration and projects an operable projection 15 to the outside. When the operable projection 15 is stopped to a bend section which is a lower side of the slit, the expansion piece 18 is urged downward by a pressing force in a direction of inner side of the connection pieces 20. When the operable projection 15 is stopped to the bend section which is an upper side of the slit, the expansion piece 18 is moved upward against the urging force in the direction of the inner side of the connection pieces 20, then the connection pieces 20 are expanded.