PURPOSE: To realize high detecting precision and high durability with the small number of parts in an axle load detecting device of a rear two-wheeled vehicle.

CONSTITUTION: Respective one ends of two operating rods 10 having the same lever ratio are engaged with each other on both sides across a center shaft 8a of a butterfly 8, these operating rods 10 are respectively supported on a chassis frame 4 side through supporting shafts 11 horizontally positioned in the longitudinal direction at equal distances from the center shaft 8a of the butterfly 8 so as to be freely and vertically oscillated, the other ends of respective operating rods 10 are respectively connected to a rear-front shaft 1 and a rear-rear shaft 2 side through wires 16, and spring means 17 for energizing respective operating rods 10 to the rotational direction to pull these wires 16 are provided. An axle load sensor part 7 is fixed on the chassis frame 4 side, and a lever 7a of the axle load sensor part 7 is connected to the center shaft 8a of the butterfly 8.