The invention provides a wavelength conversion device and a projector. The wavelength conversion device is configured to receive an excitation beam and includes a substrate, at least one wavelength conversion material layer, a driving unit and an assembly member. The substrate has a first region and a second region disposed adjacent to each other. The at least one wavelength conversion material layer is disposed on the substrate and located in the first region and configured to convert a wavelength of the excitation beam. The driving unit includes a rotation shaft. The driving unit is connected to the substrate and configured to drive the substrate to rotate with the rotation shaft as an axial center. The assembly member is disposed on the substrate, and the substrate drives the assembly member to rotate. A thickness or a shape of the assembly member is asymmetrical in a radial direction.