Method for producing core/shell type semiconductor nanoparticle and semiconductor nanoparticle composite

A method for producing a core/shell type semiconductor particle comprising

• a shell forming process at which a raw material zinc carboxylate salt and a group VI element precursor are added to a core particle dispersion solution to cause a reaction between the raw material zinc carboxylate salt and the group VI element precursor in the presence of the core particle to form a shell that includes zinc and a group VI element on a surface of the core particle, wherein
• a ratio of carboxylic acids having 8 to 10 carbon atoms in whole of carboxylic acids that form the raw material zinc carboxylate salt is 80.0% by mass or more, and
• an average branching degree of the whole of the carboxylic acids that form the raw material zinc carboxylate salt is in a range of 1.1 to 2.9.