To provide a readily handleable cooling apparatus capable of sufficiently requiring a small installation space and easily responding to a high-speed line and having a simple structure at a low cost.

This cooling apparatus is designed to make a cooling liquid 16a flow from the side of a feeding part into the side of a takeout part in a water flow passage unit 23 prepared by forming the lower part provided with the feeding part for feeding a bag unit 12 housing and hermetically sealing a small bag package in the bag unit 12 equipped with an air vent valve at a required site and an opening with an opening/closing means on the other side and then venting the air or housing the small bag package from the opening with the opening/closing means into the bag unit 12 having the opening with the opening/closing means at the required site, venting the air from the interior of the bag unit 12, hermetically sealing the bag unit 12 and venting the air and the takeout part for taking out the bag unit 12 into a circular arclike cross-sectional shape. The bag unit 12 fed from the side of the feeding part of the water flow passage unit 23 is made to float on the cooling liquid 16a in the water flow passage unit 23 and the bag unit 12 is rotated and transferred in the direction of the takeout part while rotating and stirring the cooling liquid 16a with a jet stream nozzle 25 having a jet stream nozzle orifice arranged from the lateral face part of the water flow passage unit 23 toward the base so as to feed the bag unit 12 into the cooling liquid 16a and cool the bag unit 12.