PURPOSE: To furnish an in-furnace carrier device to reduce generation of heat bending and a skid mark by heating a treated material uniformly.

CONSTITUTION: An in carrier device 7 consisting of a fixed beam 8 and a movable beam 11 is to uniformly heat-treat a treated material W by way of moving it in the forward direction on the fixed beam 8 by making the fixed beam 8 a roller free to reversely roll. Additionally, it is possible to constitute to certainly place the treated material W even when it is a steel pipe or others by providing a material holding part with a specified pitch in the shaft direction on the upper surface part of the movable beam 11 as well as providing the material holding part with a specified pitch on the outer peripheral surface of the fixed beam 8 in its shaft direction.