PURPOSE: To detect an angle in the tensile force direction from a load by an action of a tensile force, by a simple constitution, by constituting the titled instrument so that a load working on a shaft end part of a roller from a network object can be measured as angle information of the network object.

CONSTITUTION: The titled instrument installs horizontally a horizontal roller 14 so that it can be rotated by bearing devices 30L, 30R which have been fixed to a substrate 10, and also constituted of vertical rollers 20, 22 which have been installed vertically in the vicinity of a line hole of the roller 14. A load measuring mechanism for measuring a load working on both shaft end parts of the roller 14 is installed to the devices 30L, 30R. By the load working on the roller 14, pressure detectors 46, 48 measure each load in the vertical and horizontal directions, respectively, among loads working on its shaft end part 52. Also, the detectors 46, 48 generate an electric output corresponding to the load. Accordingly, a dip of a trunk rope 4 being a network object which is varied every moment can be calculated, and also, a horizontal angle of the trunk rope 4 can be calculated from a measured value of each measuring instrument 46 of the shaft end part side.