All the fruits laid in one layer in the shelf are designed for exposure to horizontal air streams. Air passes mostly on the upper surface of laid fruits and also partly on the lower surface through openings underneath the fruits layer. Fruit contact with vapor heat is better than that of the blow-in type treatment and gets closer to that of the differential pressure treatment. However, because the course of air stream is not fully restrained, the basic problem remains that more air flows over the top surface of treated fruits while the flow is much less in the air-resistant space such as the contact points between fruits and the lower side of fruit layers.