To provide a small/simply structured device that efficiently separates oil and solid contents from wastewater in minuscule-scale firms, small-scale establishments, and the like that discharge the wastewater containing the oil and solid contents.

The separation device of wastewater containing waste oil and solid contents including a ceiling-open container having a waste oil or wastewater discharge pipe with an opening/closing valve on a bottom and one solid content separating/storing tank or more installed in the open ceiling of the ceiling open container, wherein the waste oil or wastewater discharge pipe with opening/closing valve is composed of a transparent pipe coupled with a waste oil or wastewater discharge port at the bottom of the ceiling-open container, a pipe having an opening/closing valve coupled with the transparent pipe, and a pipe that is coupled with the opening/closing valve and promotes the separation of oil and water is provided.