An object selecting device for selecting a selection object from a collection of objects including the selection object, comprising: a container including an inner bottom part and configured to store liquid; a plate having a top surface and a bottom surface, including a plurality of through holes at a support position for the selection object, each of the through holes penetrating from the top surface to the bottom surface, and to be immersed in the liquid stored in the container; a determining means arranged below the container and including a microscope for observing from below the container whether or not the object supported at the support position is desired; and a removing means arranged above the container and configured to remove the object determined to be defective by the determining means and leaving only the selection object in a state supported at the support position, characterized in that; the through hole includes tapered walls that form pointed portions between tapered portions of the through hole such that when an object immersed in a liquid precipitates under gravity, it is brought into contact with the inner wall surface of the through hole, and an opening area at the upper end of the tapered portion is larger than an opening area at the lower end of the tapered portion, the determining means observes the objects supported at the support position, the supported objects having a size allowing to be introduced into the through hole from the upper ends of the tapered portions while not allowing to pass through the lower ends of the tapered portions, for determining whether or not the objects are desired, and the removing means removes the objects determined to be defective by the determining means out of the objects supported by the inner wall surface. a container including an inner bottom part and configured to store liquid; a plate having a top surface and a bottom surface, including a plurality of through holes at a support position for the selection object, each of the through holes penetrating from the top surface to the bottom surface, and to be immersed in the liquid stored in the container; a determining means arranged below the container and including a microscope for observing from below the container whether or not the object supported at the support position is desired; and a removing means arranged above the container and configured to remove the object determined to be defective by the determining means and leaving only the selection object in a state supported at the support position, characterized in that; the through hole includes tapered walls that form pointed portions between tapered portions of the through hole such that when an object immersed in a liquid precipitates under gravity, it is brought into contact with the inner wall surface of the through hole, and an opening area at the upper end of the tapered portion is larger than an opening area at the lower end of the tapered portion, the determining means observes the objects supported at the support position, the supported objects having a size allowing to be introduced into the through hole from the upper ends of the tapered portions while not allowing to pass through the lower ends of the tapered portions, for determining whether or not the objects are desired, and the removing means removes the objects determined to be defective by the determining means out of the objects supported by the inner wall surface.