A method for manufacturing a decorated article by decorating an undecorated uneven surface of an undecorated base material, the undecorated base material being a molded body of a glass fiber reinforced plastic whose undecorated uneven surface has an arithmetic average roughness (Ra) exceeding 0.5μm and being equal to or less than 5.0μm and, the method comprising: determining an ink amount to be jetted, wherein the ink amount is determined by defining the arithmetic average roughness (Ra) of the undecorated uneven surface as A and calculating the ink amount in a way in which the ink is jetted to the printing surface in which the arithmetic average roughness (Ra) is zero, such that when the calculated ink amount is jetted, the average thickness of the cured smooth ink layer becomes B, wherein B is defined in a range between equal to or more than 1.1A and equal to or less than 2.0A; forming an uncured rough-surface ink layer on the undecorated uneven surface of the undecorated base material by performing an inkjet printing using an active energy ray curable ink, in a printing process, wherein the ink amount is determined in the previous step and is a total of the ink amount, which fills the unevenness of the undecorated uneven surface, and the ink amount which is a surplus amount for a safety to obtain a smooth surface in all products; disposing a temporary cover film to cover an upper surface of the uncured rough-surface ink layer in a coating process; forming an uncured smooth ink layer in a pressing process by applying a pressing force to the uncured rough-surface ink layer through the temporary cover film from the upper surface of the temporary cover film, and smoothing a surface of the uncured rough-surface ink layer contacting with the temporary cover film; forming the cured smooth ink layer in a curing process by applying an active energy ray through the temporary cover film from the upper surface of the temporary cover film, and curing the uncured smooth ink layer, wherein the arithmetic average roughness (Ra) of a surface of the cured smooth ink layer is equal to or less than 0.5μm; and obtaining the decorated article in which a cured smooth ink layer is mounted on the undecorated uneven surface of the undecorated base material by peeling the temporary cover film in a peeling process. determining an ink amount to be jetted, wherein the ink amount is determined by defining the arithmetic average roughness (Ra) of the undecorated uneven surface as A and calculating the ink amount in a way in which the ink is jetted to the printing surface in which the arithmetic average roughness (Ra) is zero, such that when the calculated ink amount is jetted, the average thickness of the cured smooth ink layer becomes B, wherein B is defined in a range between equal to or more than 1.1A and equal to or less than 2.0A; forming an uncured rough-surface ink layer on the undecorated uneven surface of the undecorated base material by performing an inkjet printing using an active energy ray curable ink, in a printing process, wherein the ink amount is determined in the previous step and is a total of the ink amount, which fills the unevenness of the undecorated uneven surface, and the ink amount which is a surplus amount for a safety to obtain a smooth surface in all products; disposing a temporary cover film to cover an upper surface of the uncured rough-surface ink layer in a coating process; forming an uncured smooth ink layer in a pressing process by applying a pressing force to the uncured rough-surface ink layer through the temporary cover film from the upper surface of the temporary cover film, and smoothing a surface of the uncured rough-surface ink layer contacting with the temporary cover film; forming the cured smooth ink layer in a curing process by applying an active energy ray through the temporary cover film from the upper surface of the temporary cover film, and curing the uncured smooth ink layer, wherein the arithmetic average roughness (Ra) of a surface of the cured smooth ink layer is equal to or less than 0.5μm; and obtaining the decorated article in which a cured smooth ink layer is mounted on the undecorated uneven surface of the undecorated base material by peeling the temporary cover film in a peeling process.