Abstract: Apparatus for cooling or heating articles carried on a spiral conveyor helically rotating round the outer periphery of a drum, wherein the diameter of the drum is reduced, a blower port and a suction port being provided on the peripheral wall encircling the spiral conveyor, said blower port and suction port being adapted to communicate with each other with interposition of a heat exchanger and fans, air cooled or heated in the heat exchanger being blown through the blower port, the air being spontaneously bifurcated to both sides of the small diameter drum to be recombined at the suction port, the recombined air being cooled or heated in the heat exchanger for circulation through the blower port so that the drum is cooled or heated speedily and efficiently through the whole periphery thereof, thereby enabling not only to economize the cost and time required for cooling or heating but also to minimize the dimensions of the whole apparatus for the reduction of the space necessitated for the installation.