A method of manufacturing an organic light emitting display apparatus includes: preparing a substrate having a first surface and a second surface opposite to the first surface; forming a through-hole penetrating the substrate from the first surface to the second surface; forming a humidity preventing layer on the substrate; forming a plurality of organic light emitting diodes on the substrate; and removing an organic light emitting diode adjacent to the through-hole from among the plurality of organic light emitting diodes, in which the humidity preventing layer may be formed on the substrate via a sequential vapor infiltration (SVI) process.