Resin powder for solid freeform fabrication characterized in that the resin powder has a 50 percent cumulative volume particle diameter of from 5 to 100 μm and a ratio (Mv/Mn) of a volume average particle diameter (Mv) to a number average particle diameter (Mn) of 2.50 or less, wherein the 50 percent cumulative volume particle diameter and Mv/Mn is measured by particle size distribution measuring device (microtrac MT3300 EXII, manufactured by MicrotracBEL Corp), and satisfies at least one of the following conditions to:: Tmf1 > Tmf2 and (Tmf1 - Tmf2) ≥ 3 degrees C, where Tmf1 represents a melting starting temperature of an endothermic peak as the resin powder is heated to a temperature 30 degrees C higher than a melting point of the resin powder at a temperature rising speed of 10 degrees C per minute for a first time and Tmf2 represents a melting starting temperature of an endothermic peak as the resin powder is heated for the first time, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute for a second time, and both Tmf1 and Tmf2 are measured in differential scanning calorimetry measuring according to ISO 3146, wherein the melting starting temperature of the endothermic peak represents a temperature at a point -15 mW lower from a straight line parallel to X axis drawn from a site where quantity of heat becomes constant after endotherm at the melting point finishes to a lower temperature side,: Cd1 > Cd2 and (Cd1 - Cd2) ≥ 3 percent, where Cd1 represents a crystallinity obtained from an energy amount of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a temperature rising speed of 10 degrees C per minute for a first time and Cd2 represents a crystallinity obtained from an energy amount of the endothermic peak as the resin powder is heated for the first time, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute for a second time, and both Cd1 and Cd2 are measured in differential scanning calorimetry measuring according to ISO 3146, and: C × 1 > C × 2 and (C × 1 - C × 2) ≥ 3 percent, where C × 1 represents a crystallinity of the resin powder obtained by X-ray diffraction measuring and C × 2 represents a crystallinity obtained by X-ray diffraction measuring as the resin powder is heated to the temperature 30 degrees C higher than the melting point thereof at a temperature rising speed of 10 degrees C per minute, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and thereafter heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute in nitrogen atmosphere.: Tmf1 > Tmf2 and (Tmf1 - Tmf2) ≥ 3 degrees C, where Tmf1 represents a melting starting temperature of an endothermic peak as the resin powder is heated to a temperature 30 degrees C higher than a melting point of the resin powder at a temperature rising speed of 10 degrees C per minute for a first time and Tmf2 represents a melting starting temperature of an endothermic peak as the resin powder is heated for the first time, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute for a second time, and both Tmf1 and Tmf2 are measured in differential scanning calorimetry measuring according to ISO 3146, wherein the melting starting temperature of the endothermic peak represents a temperature at a point -15 mW lower from a straight line parallel to X axis drawn from a site where quantity of heat becomes constant after endotherm at the melting point finishes to a lower temperature side,: Cd1 > Cd2 and (Cd1 - Cd2) ≥ 3 percent, where Cd1 represents a crystallinity obtained from an energy amount of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a temperature rising speed of 10 degrees C per minute for a first time and Cd2 represents a crystallinity obtained from an energy amount of the endothermic peak as the resin powder is heated for the first time, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute for a second time, and both Cd1 and Cd2 are measured in differential scanning calorimetry measuring according to ISO 3146, and: C × 1 > C × 2 and (C × 1 - C × 2) ≥ 3 percent, where C × 1 represents a crystallinity of the resin powder obtained by X-ray diffraction measuring and C × 2 represents a crystallinity obtained by X-ray diffraction measuring as the resin powder is heated to the temperature 30 degrees C higher than the melting point thereof at a temperature rising speed of 10 degrees C per minute, cooled down to -30 degrees C or lower at a temperature falling speed of 10 degrees C per minute, and thereafter heated to the temperature 30 degrees C higher than the melting point at a temperature rising speed of 10 degrees C per minute in nitrogen atmosphere.