A method of manufacturing a laminated iron core using a die, includes punching out iron core pieces from a thin steel sheet material by a first working row, each piece having a spindle hole and a plurality of slot holes of a given configuration. Electrically insulating sheet pieces are punched out from an electrically insulating thin sheet material by a second working row, each piece having a spindle hole and a plurality of slot holes with a configuration similar to, but smaller than, the slot holes of the iron core pieces. Thereafter, the iron core pieces and electrically insulating sheet pieces are stacked such that edges of the slot holes of the electrically insulating sheet pieces extend outwardly beyond edges of the slot holes of the iron core pieces.