To provide a balloon-releasing device and a balloon-releasing method capable of surely performing balloon release at a cold district, such as a polar region or balloon release under inclement weather with a simple constitution, and dispensing with suppression of the weight of a meteorological observation apparatus.

This device has a constitution, wherein the balloon 3 is directly or indirectly connected to the meteorological observing apparatus 18 by a support string 11 so as to maintain a state, where a suspension string 10 for connecting the balloon 3 to the meteorological observion apparatus 18 is wound on a lowering device 6, and the support string 11 is cut by being heated with a nichrome wire 14b by a power source 12, after the lapse of a prescribed time, after balloon release.