It was difficult to create a thin bio sample embedded in an embedding material without using an expensive microtome. The present invention provides a medical device having a space for assisting in the embedding of a bio sample in an embedding material, the medical device being provided with a cover part and a base part having a recessed section in which the space is created by covering the cover part, wherein the base part is provided with a flow passage having an inlet section that is in fluid communication with the space, and the flow passage is configured such that when a force is applied to the medical device so that the volume of the space decreases, the embedding material flows out while preventing a positional misalignment of the bio sample inside the embedding material.