A thermoacoustic apparatus capable of reducing the time elapsed until an acoustic wave is generated and improving the energy conversion efficiency significantly is provided. In order to solve the above-described issues, in a thermoacoustic apparatus 1 including a pair of heat exchangers 41 and 43 separately set on the high temperature side and on the low temperature side, a second stack 42 which is sandwiched between the heat exchangers 41 and 43 and which has a plurality of transmission paths in the inside, and a loop tube 2 provided with the heat exchangers 41 and 43 and the stack 42, the thermoacoustic apparatus converting acoustic energy generated in the loop tube 2 with an acoustic wave generator 3 to thermal energy by using the heat exchangers 41 and 43 and the stack 42, a narrow portion 21 in which the inner diameter is relatively reduced is disposed at a position at which the particle velocity of a standing wave generated in the loop tube 2 is in the vicinity of a maximum. Furthermore, in order to reduce the particle velocity, a branch tube 2e is connected at a position at which the particle velocity of a standing wave generated in the loop tube 2 is in the vicinity of a minimum.