A sealed rotating container that is used for a centrifugal smearing device and houses a chamber with a slide glass removably attached for holding a liquid sample and smearing cells in the liquid sample onto the slide glass with a centrifugal force, said sealed rotating container comprising: a main body being capable of housing said chamber: and a lid configured to close an upper face opening portion of the main body, and having a storage section for storing liquid scattered from the chamber during being centrifuged, formed on an inside face of the main body, characterized in that an unbalanced-load prevention mechanism for preventing unbalanced-load of liquid stored in said storage section is provided, wherein: i) said unbalanced-load prevention mechanism includes a plurality of ribs extending in a vertical direction and projecting inward from an inner wall face of said storage section; or ii) said unbalanced-load prevention mechanism is an unbalanced-load prevention member formed of a member different from that of said main body, is capable of being mounted to said storage section of said main body, and includes a plurality of ribs extending in a vertical direction and projecting inward; or iii) said unbalanced-load prevention mechanism is formed in a shape which increases a frictional resistance between an inner wall face of said storage section and liquid components; or iv) said unbalanced-load prevention mechanism is an unbalanced-load prevention member formed of a member different from that of said main body, is capable of being mounted to said storage section of said main body, and is formed in a shape which increases a frictional resistance between an inner wall face and liquid components; or v) said main body includes a rotor to which a plurality of said chambers is capable of being mounted; and said unbalanced-load prevention mechanism is a plurality of dividers projecting from an outer circumferential edge of said rotor toward said storage section. i) said unbalanced-load prevention mechanism includes a plurality of ribs extending in a vertical direction and projecting inward from an inner wall face of said storage section; or ii) said unbalanced-load prevention mechanism is an unbalanced-load prevention member formed of a member different from that of said main body, is capable of being mounted to said storage section of said main body, and includes a plurality of ribs extending in a vertical direction and projecting inward; or iii) said unbalanced-load prevention mechanism is formed in a shape which increases a frictional resistance between an inner wall face of said storage section and liquid components; or iv) said unbalanced-load prevention mechanism is an unbalanced-load prevention member formed of a member different from that of said main body, is capable of being mounted to said storage section of said main body, and is formed in a shape which increases a frictional resistance between an inner wall face and liquid components; or v) said main body includes a rotor to which a plurality of said chambers is capable of being mounted; and said unbalanced-load prevention mechanism is a plurality of dividers projecting from an outer circumferential edge of said rotor toward said storage section.