A three-dimensional object manufacturing method for manufacturing a three-dimensional object by ejecting a liquid shaping material and then solidifying the ejected shaping material includes: an interior forming process of forming an interior portion of the three-dimensional object by the shaping material; and a periphery forming process of forming a peripheral portion of a periphery of the interior portion by stacking a plurality of layers by the shaping material, where the shaping material for forming the interior portion in the interior forming process has a larger rigidity in a solid state compared to the shaping material for forming the peripheral portion in the periphery forming process, the periphery forming process is a process of forming a groove configuring one part of the peripheral portion, and the interior forming process is a process of forming the interior portion by placing the liquid shaping material in the groove.