A continuous-cast slab is provided where central porosity is reduced by surly crushing the slab. A method and apparatus of manufacturing the slab is also provided. The continuous-cast slab having horizontally symmetrical granular equiaxed crystals at least in the center in the thickness direction includes a first reduction dent and a second reduction dent that further dents from the bottom surface of the first reduction dent and is narrower than the first reduction dent at least on one long side surface. Such a configuration can makes it possible to achieve the continuous-cast slab of no more than 2.5×10−4 cm3/g in a maximum porosity volume while segregation is reduced.