Gas-barrier plastic molded product and manufacturing process therefor

The purpose of the present invention is to provide a gas-barrier plastic molded product which exhibits high gas-barrier properties. This gas-barrier plastic molded product is equipped with a plastic molded product and a gas-barrier thin film provided on the surface of the plastic molded product, said gas-barrier thin film comprising silicon (Si), carbon (C), oxygen (O) and hydrogen (H) as constituent elements and including an Si-containing layer that has an Si content of 40.1% or more as defined by numerical formula (1): Si content [%] = {(Si content[atomic %])/(total content [atomic %] of Si, O and C)} × 100 [wherein the contents of Si, O and C are proportions thereof among the three elements].