A composite prepreg base which includes a raw prepreg base comprising a fiber sheet comprising discontinuous reinforcing fibers arranged in one direction and having a fiber length of 1-300 mm and a matrix resin infiltrated into the fiber sheet; and an additional resin layer formed on at least one surface of the raw prepreg base. The composite prepreg base is produced by a process including (i) the step of preparing the raw prepreg base and (ii) the step of forming an additional resin layer on at least one surface of the raw prepreg base prepared. Also provided are: a layered base including two or more sheets of the composite prepreg base which have been superposed so that the additional resin layer is present on at least one surface; and a fiber-rein-forced plastic formed by heating and pressing the layered base.