A wavelength converter comprising: a substrate portion; and an optical conversion layer including optical conversion inorganic particles and an inorganic binder portion that mutually holds the optical conversion inorganic particles, and being formed on the substrate portion, wherein the inorganic binder portion includes: an amorphous binder; and granular binder particulates with an average particle size smaller than an average particle size of the optical conversion inorganic particles, and wherein, in a case where, in the optical conversion layer, a portion present close to the substrate portion with respect to an intermediate plane in a thickness direction of the optical conversion layer is defined as a substrate-side portion, and a portion present remote from the substrate portion with respect to the intermediate plane is defined as a non-substrate-side portion, when a ratio of an average volume concentration of the binder particulates in the substrate-side portion with respect to an average volume concentration of the optical conversion inorganic particles in the substrate-side portion is defined as a substrate-side binder particulate concentration ratio RFs and, when a ratio of an average volume concentration of the binder particulates in the non-substrate-side portion with respect to an average volume concentration of the optical conversion inorganic particles in the non-substrate-side portion is defined as a non-substrate-side binder particulate concentration ratio RFo, the substrate-side binder particulate concentration ratio RF S is larger than the non-substrate-side binder particulate concentration ratio RFo. a substrate portion; and an optical conversion layer including optical conversion inorganic particles and an inorganic binder portion that mutually holds the optical conversion inorganic particles, and being formed on the substrate portion, wherein the inorganic binder portion includes: an amorphous binder; and granular binder particulates with an average particle size smaller than an average particle size of the optical conversion inorganic particles, and wherein, in a case where, in the optical conversion layer, a portion present close to the substrate portion with respect to an intermediate plane in a thickness direction of the optical conversion layer is defined as a substrate-side portion, and a portion present remote from the substrate portion with respect to the intermediate plane is defined as a non-substrate-side portion, when a ratio of an average volume concentration of the binder particulates in the substrate-side portion with respect to an average volume concentration of the optical conversion inorganic particles in the substrate-side portion is defined as a substrate-side binder particulate concentration ratio RFs and, when a ratio of an average volume concentration of the binder particulates in the non-substrate-side portion with respect to an average volume concentration of the optical conversion inorganic particles in the non-substrate-side portion is defined as a non-substrate-side binder particulate concentration ratio RFo, the substrate-side binder particulate concentration ratio RF S is larger than the non-substrate-side binder particulate concentration ratio RFo.