The invention provides a particulate construct such as microcapsules containing a drug, and serving a slow releasing preparation not associated with a practically unacceptable initial burst release but showing a practically acceptable zero-order release for a certain period and a producing method for such particulate construct, and a slow releasing preparation of a high drug content capable of stably incorporating the drug in the particulate construct such as microcapsules, and a producing method for such preparation. The invention also provides a particulate construct such as microcapsules utilizing a highly functional polymer compound and incorporating oil phase and/or water phase in solid phase, and a producing method therefor. Furthermore, the invention provides a particulate construct such as microcapsules having a hollow structure of a single polymer membrane as the outer shell and capable of containing many bubbles in the fine particles, and a producing method capable of preparing such construct with a high reproducibility. According to the invention, a particulate construct such as microcapsules is formed with polyhydroxyalkanoate of a specified structure and a drug for a desired purpose, an oil phase and/or a water phase, or a gaseous phase is included in such construct.