According to one embodiment, an acoustic semiconductor device includes an element unit, and a first terminal. The element unit includes an acoustic resonance unit. The acoustic resonance unit includes a semiconductor crystal. An acoustic standing wave is excitable in the acoustic resonance unit and is configured to be synchronously coupled with electric charge density within at least one portion of the semiconductor crystal via deformation-potential coupling effect. The first terminal is electrically connected to the element unit. At least one selected from outputting and inputting an electrical signal is implementable via the first terminal. The electrical signal is coupled with the electric charge density. The outputting the electrical signal is from the acoustic resonance unit, and the inputting the electrical signal is into the acoustic resonance unit.