An intermediate base material is provided that is excellent in the conformity to three-dimensional shapes and that, when formed into a fiber reinforced plastic, develops good surface quality and high mechanical properties.
According to one aspect, an incised prepreg is provided that has, in at least a partial region in a prepreg that contains unidirectionally oriented reinforcing fibers and a resin, a plurality of incisions that divide reinforcing fibers, wherein, in the case where a population is made up of the numbers of incisions contained in ten small circular regions of 10 mm in diameter randomly selected in the aforementioned region, a mean value for the population is 10 or greater and a coefficient of variation therefor is within 20%.