An aerator (100, 200, 300, 400, 500) comprising: a housing defining an inner cavity and comprising at least one side wall and an upper surface connected to the at least one side wall; a first partition formed in the inner cavity and extending from a first lower end to a first upper end to define a first cavity and a second cavity; and a second partition formed between the first partition and a first side wall in the inner cavity and extending from a second upper end to a second lower end to form a first chamber and a second chamber in the second cavity, wherein the housing comprises an outlet communicating with the second chamber, the upper end of the first partition is spaced apart from the upper surface to form a first opening such that the first cavity communicates with the second cavity through the first opening, the at least one side wall comprises the first side wall and a second side wall opposite the first side wall, the first lower end of the first partition is connected to the first side wall through a lower surface, the second side wall is connected to the upper surface through a first connecting surface, the second partition is connected to the upper surface through a second connecting surface, the first chamber and the second chamber communicate with each other under the second lower end of the second partition, and each of the first connecting surface and the second connecting surface is a planar surface, a curved surface, or a polygonal surface, wherein when the first connecting surface is a curved surface, and the curved surface has the minimum radius of curvature r 1 satisfying Equation 1: a 4 ≤ r 1 ≤ a where a denotes a distance between the second side wall and the first partition, wherein when the first connecting surface is a planar surface connecting the second side wall to the upper surface, a distance x 1 between the second side wall and a point at which an extension of the second side wall joins an extension of the upper surface satisfies Equation 3, and a distance x 2 between the upper surface and the point satisfies Equation 4: a 4 ≤ x 1 ≤ a a 4 ≤ x 2 ≤ a where a is a distance between the second side wall and the first partition, and the second connecting surface is a planar surface connecting the upper surface to the second partition, a distance x 3 between the upper surface and a point at which an extension of the upper surface joins an extension of the second partition satisfies Equation 5, and a distance x 4 between the second partition and the point satisfies Equation 6: b 3 ≤ x 3 ≤ b b 3 ≤ x 4 ≤ b where b denotes a distance between the first partition and the second partition. a housing defining an inner cavity and comprising at least one side wall and an upper surface connected to the at least one side wall; a first partition formed in the inner cavity and extending from a first lower end to a first upper end to define a first cavity and a second cavity; and a second partition formed between the first partition and a first side wall in the inner cavity and extending from a second upper end to a second lower end to form a first chamber and a second chamber in the second cavity, wherein the housing comprises an outlet communicating with the second chamber, the upper end of the first partition is spaced apart from the upper surface to form a first opening such that the first cavity communicates with the second cavity through the first opening, the at least one side wall comprises the first side wall and a second side wall opposite the first side wall, the first lower end of the first partition is connected to the first side wall through a lower surface, the second side wall is connected to the upper surface through a first connecting surface, the second partition is connected to the upper surface through a second connecting surface, the first chamber and the second chamber communicate with each other under the second lower end of the second partition, and each of the first connecting surface and the second connecting surface is a planar surface, a curved surface, or a polygonal surface, wherein when the first connecting surface is a curved surface, and the curved surface has the minimum radius of curvature r 1 satisfying Equation 1: a 4 ≤ r 1 ≤ a where a denotes a distance between the second side wall and the first partition, wherein when the first connecting surface is a planar surface connecting the second side wall to the upper surface, a distance x 1 between the second side wall and a point at which an extension of the second side wall joins an extension of the upper surface satisfies Equation 3, and a distance x 2 between the upper surface and the point satisfies Equation 4: a 4 ≤ x 1 ≤ a a 4 ≤ x 2 ≤ a where a is a distance between the second side wall and the first partition, and the second connecting surface is a planar surface connecting the upper surface to the second partition, a distance x 3 between the upper surface and a point at which an extension of the upper surface joins an extension of the second partition satisfies Equation 5, and a distance x 4 between the second partition and the point satisfies Equation 6: b 3 ≤ x 3 ≤ b b 3 ≤ x 4 ≤ b where b denotes a distance between the first partition and the second partition.