A thermally expandable sheet includes a base, a thermally expansive layer, and a color adjustment layer. The thermally expansive layer is provided on a first side of the base and includes a thermally expandable material that distends in accordance with an amount of heat absorbed, the heat being generated from a thermal conversion layer that includes a thermal conversion material that converts electromagnetic waves to heat. The color adjustment layer is provided on at least one of the thermally expansive layer and a second side of the base and includes a color adjusting agent. When the thermal conversion layer is provided on the color adjustment layer, the color adjustment layer reduces a visual difference in color between a first region where the thermal conversion layer is provided and a second region where the thermal conversion layer is not provided.