A cyclonic separator and a vacuum cleaner which efficiently separates dust, collect the dust without re-scattering it and make low noise are provided. In a primary cyclone portion 10, a primary swirl chamber 12 swirls air containing dust sucked from a primary inlet 11, and thereby, separates a first dust and a second dust from the air containing dust to collect them respectively in a zero-order dust case 114 which is provided at a side of the primary swirl chamber 12 and communicates with a zero-order opening portion 113 provided at a side wall, and a primary dust case 14 provided at a lower side of the primary swirl chamber 12. In a secondary cyclone portion 20, a secondary inlet 21 with an opening area smaller than that of a primary outlet body 15 sucks air exhausted from the primary outlet body 15, a secondary swirl chamber 22 swirls the first air to separate the second dust which is finer than the first dust from the first air to collect the second dust in a secondary dust case 24 provided at a lower side of the secondary swirl chamber 12. With regard to the cyclonic separator with such a configuration, the zero-order dust case 114 is formed to cover at least a part of the secondary cyclone portion 20.