A color conversion element (1, 1C, 1D, 1E), comprising: a substrate (2, 2e); a phosphor portion that is disposed above the substrate, and is configured to receive laser light transmitted from an outside on a first principal surface of the phosphor portion on the side opposite to the substrate (2, 2e) and to emit light in a color different from a color of the laser light; a reflective layer that includes a dielectric multilayer film and is disposed on a second principal surface of the phosphor portion, the second principal surface of the phosphor portion being a surface facing the substrate (2, 2e); and a joining portion (5, 5c, 5d, 5e) that is interposed between the reflective layer and the substrate (2, 2e) to join the reflective layer and the substrate (2, 2e), wherein the joining portion (5, 5c, 5d, 5e) includes an air layer (53, 53c, 53d) that exposes the reflective layer in a position where the air layer (53, 53c, 53d) at least partially overlaps an irradiation region in a plan view, the irradiation region being a region configured to be irradiated with the laser light on the phosphor portion, wherein the phosphor portion and the reflective layer each have an annular shape in the plan view, and the joining portion (5c, 5d) only joins the substrate and an outer peripheral portion of the reflective layer located in a more outward position than the irradiation region, wherein the joining portion (5, 5c, 5e) includes a first joining portion (51, 51c) and a second joining portion (52, 52c), and the air layer (53, 53c) is formed between the first joining portion (51, 51c) and the second joining portion (52, 52c), or the joining portion is formed in an annular shape in a plan view, and the portion of the joining portion in a more inward position than the irradiation region is the air layer as a whole. a substrate (2, 2e); a phosphor portion that is disposed above the substrate, and is configured to receive laser light transmitted from an outside on a first principal surface of the phosphor portion on the side opposite to the substrate (2, 2e) and to emit light in a color different from a color of the laser light; a reflective layer that includes a dielectric multilayer film and is disposed on a second principal surface of the phosphor portion, the second principal surface of the phosphor portion being a surface facing the substrate (2, 2e); and a joining portion (5, 5c, 5d, 5e) that is interposed between the reflective layer and the substrate (2, 2e) to join the reflective layer and the substrate (2, 2e), wherein the joining portion (5, 5c, 5d, 5e) includes an air layer (53, 53c, 53d) that exposes the reflective layer in a position where the air layer (53, 53c, 53d) at least partially overlaps an irradiation region in a plan view, the irradiation region being a region configured to be irradiated with the laser light on the phosphor portion, wherein the phosphor portion and the reflective layer each have an annular shape in the plan view, and the joining portion (5c, 5d) only joins the substrate and an outer peripheral portion of the reflective layer located in a more outward position than the irradiation region, wherein the joining portion (5, 5c, 5e) includes a first joining portion (51, 51c) and a second joining portion (52, 52c), and the air layer (53, 53c) is formed between the first joining portion (51, 51c) and the second joining portion (52, 52c), or