To provide an outrigger to be attached on a trestle such as a stepladder, wherein the freedom of installation position on the trestle is raised, which can be operated easily, and which can be increased in size without inviting structural complication when required.

The outrigger comprises a pair of upper and lower swinging pivot parts 7 and 9 separately provided in the upper part and the lower part, an upper leg part 5 swingably held on the upper swinging pivot part 7 of the pair in a downwardly swinging direction, a lower leg part 6 held on the upper leg part 5 slidably along the longitudinal direction and an opening setting link 8 having both ends connected swingably between the lower leg part 6 and the lower swinging pivot part 9.