To provide a load transmission mechanism capable of transmitting a constant load to a load cell through the frame and capable of reducing a span error.

In the load transmission mechanism constituting the Roberval mechanism for transmitting the load to the load cell, the load transmission member, at least the direct upper surface of the load cell fixing part is recessed lower by one step for keeping it noncontact with the cover member. If the position of the center of gravity of the object mounted on the cover member is same, the difference of affection of the deformation of the load transmission member or the moment applied on the load cell is reduced, and transmission of the constant load to the load cell via the load transmission member is made possible. Therefore, the span error generated depending on the loading position can be reduced, regardless of the concentrated load or distributed load.