PURPOSE: To provide power truck mounting structure capable of preventing excessive external force that works on a power truck when telescopic rails are displaced in the longitudinal direction.

CONSTITUTION: In the power truck mounting structure of a container spreader, the rail side end plate 5a of a power truck 5 for guiding the follow-up motion to the telescopic rails 3, of the hydraulic piping and the like arranged between a rail holder 2 and the telescopic rails 3 is mounted on a mounting bracket 10 with a slotted hole 10a, which is fixed to the telescopic rails 3 by mounting bolts 14 through a pair of upper and lower mounting plates 11 and pad so as to enables the power truck 5 to relatively move in the longitudinal direction in the range of the long hole 10a of the mounting bracket 10 when the telescopic rails 3 are displaced in the longitudinal direction.