A cooling device (10, 110, 210) configured to cool a heating element, wherein the cooling device (10, 110, 210) comprising: a cooling chamber (11, 111, 211), cooling the heating element by a first cooling medium; a radiator chamber (12, 112, 212), releasing heat of the first cooling medium to an outside; and a first connection path (13, 113, 213, 217) and a second connection path (14, 114, 214, 218), connecting the cooling chamber (11, 111, 211) to the radiator chamber (12, 112, 212), wherein at least a part of the radiator chamber (12, 112, 212) is positioned above the cooling chamber (11, 111, 211) in a vertical direction, wherein a part in which the first connection path (13, 113, 213, 217) is connected to the radiator chamber (12, 112, 212) is positioned at a same part in which the first connection path (13, 113, 213, 217) is connected to the cooling chamber (11, 111, 211) in the vertical direction or is positioned above a part in which the first connection path (13, 113, 213, 217) is connected to the cooling chamber (11, 111, 211), and when a part of the first cooling medium in the cooling chamber (11, 111, 211) is vaporized, at least a part of the vaporized first cooling medium moves into the first connection path (13, 113, 213, 217), and a circulation is generated in which the first cooling medium in the cooling chamber (11, 111, 211) flows to the radiator chamber (12, 112, 212) through the first connection path (13, 113, 213, 217), and the first cooling medium in the radiator chamber (12, 112, 212) flows into the cooling chamber (11, 111, 211) through the second connection path (14, 114, 214, 218);wherein the heating element is housed in the cooling chamber (11, 111, 211), and the first cooling medium comes directly in contact with the heating element. characterized in that a size of the first connection path (13, 113, 213, 217) in a direction orthogonal to a direction in which the first connection path (13, 113, 213, 217) extends and a size of the second connection path (14, 114, 214, 218) in a direction orthogonal to a direction in which the second connection path (14, 114, 214, 218) extends are of a size at which at least a part of the vaporized first cooling medium is retained in the first connection path (13, 113, 213, 217) when the temperature of the heating element increases, such that a pressure difference is generated between a first part and a second part, wherein the first part is the part in which the first connection path is connected to the cooling chamber and the second part is the part in which the second connection path is connected to the cooling chamber. a cooling chamber (11, 111, 211), cooling the heating element by a first cooling medium; a radiator chamber (12, 112, 212), releasing heat of the first cooling medium to an outside; and a first connection path (13, 113, 213, 217) and a second connection path (14, 114, 214, 218), connecting the cooling chamber (11, 111, 211) to the radiator chamber (12, 112, 212), wherein at least a part of the radiator chamber (12, 112, 212) is positioned above the cooling chamber (11, 111, 211) in a vertical direction, wherein a part in which the first connection path (13, 113, 213, 217) is connected to the radiator chamber (12, 112, 212) is positioned at a same part in which the first connection path (13, 113, 213, 217) is connected to the cooling chamber (11, 111, 211) in the vertical direction or is positioned above a part in which the first connection path (13, 113, 213, 217) is connected to the cooling chamber (11, 111, 211), and when a part of the first cooling medium in the cooling chamber (11, 111, 211) is vaporized, at least a part of the vaporized first cooling medium moves into the first connection path (13, 113, 213, 217), and a circulation is generated in which the first cooling medium in the cooling chamber (11, 111, 211) flows to the radiator chamber (12, 112, 212) through the first connection path (13, 113, 213, 217), and the first cooling medium in the radiator chamber (12, 112, 212) flows into the cooling chamber (11, 111, 211) through the second connection path (14, 114, 214, 218);wherein the heating element is housed in the cooling chamber (11, 111, 211), and the first cooling medium comes directly in contact with the heating element. characterized in that a size of the first connection path (13, 113, 213, 217) in a direction orthogonal to a direction in which the first connection path (13, 113, 213, 217) extends and a size of the second connection path (14, 114, 214, 218) in a direction orthogonal to a direction in which the second connection path (14, 114, 214, 218) extends are of a size at which at least a part of the vaporized first cooling medium is retained in the first connection path (13, 113, 213, 217) when the temperature of the heating element increases, such that a pressure difference is generated between a first part and a second part, wherein the first part is the part in which the first connection path is connected to the cooling chamber and the second part is the part in which the second connection path is connected to the cooling chamber.