A thermoacoustic device includes a substrate, a sound wave generator, an insulating layer, a first electrode and a second electrode. The first electrode and the second electrode are spaced from each other and electrically connected to the sound wave generator. The substrate includes a first surface and a second surface opposite to the first surface. The first surface defines a plurality of grooves, and a bulge is formed between the adjacent two grooves. The insulating layer is located on the first surface, and continuously attached on the grooves and the bulge. The sound wave generator is located on the insulating layer. The sound wave generator defines a first portion and a second portion. The first portion is suspended on the grooves. The second portion is attached on the bulge.