To provide a thermoplastic vinyl resin composition containing uniformly dispersed ultrafine semiconductor particles.

The thermoplastic resin composition containing ultrafine particles contains, as essential components, (A) ultrafine semiconductor particles surface-modified with two or more kinds of organic low-molecular compounds selected from compounds containing an amino group, compounds containing a carboxy group, compounds containing a hydroxy group, compounds containing an amide group, compounds containing a sulfonic acid group, compounds containing sulfinic acid group, compounds containing phosphonic acid group and compounds containing phosphinic acid group and (B) a thermoplastic vinyl resin having mercapto group on the terminal.