A pharmaceutical composition includes lipid nanoparticles which include two or more of a phospholipid, cholesterol, and an ionic lipid, and a tricyclic derivative, wherein the solubility of the tricyclic derivative is improved. It is possible to solubilize a partially soluble tricyclic derivative in a high concentration even without using a solubilization aid harmful to the human body, to maintain improved solubility even if water is added for the use as an injection, and to show stability even if stored for a long time, by preparing lipid nanoparticles. Therefore, the lipid nanoparticles of the present invention can be used for preparing a pharmaceutical preparation containing a partially soluble tricyclic derivative as an active ingredient.
