Abstract: An object is to provide a coated semiconductor nanoparticle having sufficient fluorescence intensity. A method for manufacturing a coated semiconductor nanoparticle according to the present invention relates to a method for manufacturing a coated semiconductor nanoparticle containing a semiconductor nanoparticle having a core/shell structure and a translucent coating layer containing silicon coating the semiconductor nanoparticle. The method includes a step of bringing the semiconductor nanoparticle into contact with a silane compound in the presence of an antioxidant and that the antioxidant contains at least one kind selected from the group consisting of compounds containing at least one of a phosphor atom and a sulfur atom and no hydroxy group.