A manufacturing method of a picture comprises, disposing salt on a manufacturing board to form a salt layer, and coating and drying steps. In the primary coating and drying steps, polyurethane resin cured by exposure to air for about 10 to 20 minutes is poured onto the salt layer and the primary coating layer is dried in a condition of a relative humidity of 40 to 60%. In the secondary coating step, polyurethane resin cured for about 21 to 40 minutes is poured onto the primary coating layer and the secondary coating layer is dried in a condition of a relative humidity of 1 to 39%. In the tertiary coating step, polyurethane resin cured for about 50 to 70 minutes is poured onto the secondary coating layer and the tertiary coating layer is dried in a condition of a relative humidity of 1 to 39%.