A wavelength converter includes: a substrate portion; and an optical conversion layer including optical conversion inorganic particles and a binder portion that mutually holds the optical conversion inorganic particles, and being formed on the substrate portion, wherein the substrate portion and the binder portion bond to each other, and wherein the binder portion includes, as a main component, an inorganic polycrystalline substance composed in such a manner that inorganic material particles having an average particle size of 1 μm or less are bound to one another, and has thermal conductivity of 2 w/mK or more.