The characteristics of a new loop-type thermoacoustic sound wave generator, in which two closed-end connected-type generators are connected to each other at the open ends by four bent tubes and sealed hermetically, are described. It has been reported that two types of sound wave generators, in which two identically shaped systems are connected to each other at either the open ends or the closed ends, can operate stably. In the new loop-type sound wave generator, which has the benefits of the above-mentioned types of sound wave generators, the pressure, velocity amplitude, acoustic intensity, and heat transferred by sound waves are greater than those of the other connected-type ones. And harmonics in pressure signals and no harmonics in velocity signals are observed at the connected part. An optimum theoretical sound wave frequency of 100Hz is also confirmed for this type of sound wave generator.