A wavelength conversion device includes a substrate, a wavelength conversion layer disposed on the substrate and including a plurality of phosphor particles and a bonding member configured to bond the phosphor particles and the substrate to each other, and a reflecting layer disposed between the substrate and the wavelength conversion layer and configured to reflect light. A particle size distribution of the phosphor particles is no smaller than 40 μm and no larger than 200 μm. A center value of the particle size distribution is no smaller than 70 μm and no larger than 150 μm. Some of the phosphor particles are thermally coupled to the reflecting layer. 50% or more of the phosphor particles are thermally coupled to each other. A thickness of the bonding member is no smaller than 30% and no larger than 80% of a thickness of the wavelength conversion layer.