Rosin is one of the traditional sizing agents which are often used in the paper making operation. Rosin-Ester(RE) emulsion size consisting of fortified rosin, triglyceride rosin and anionic polymer surfactant, has been recently used as an internal size for neutral papermaking. In this study, the preparation of rosin-ester emulsion size and sizing effect under neutral conditions were evaluated under various conditions during handsheet-making.