To provide a friction tester equipped with a mechanism for preventing the breakage of a load cell, due to adhesion and the like generated while sliding of the friction tester with the increase of a load, and friction force abruptly and instantly increased.

In a reciprocating sliding friction tester equipped with a load cell for measuring friction force between a columnar fixed testing member and reciprocating member, the shear strength of the whole or a part of a vertical cross-section in an axial direction of the columnar fixed testing member is made to be not more than a permissible load of the load cell.