A method for the secretory production of a glycoprotein having a human-type sugar chain, comprising a step of introducing a gene of an enzyme capable of performing a transfer reaction of a galactose residue to a non-reducing terminal acetylglucosamine residue, and a gene of heterologous glycoprotein, to obtain a transformed plant cell, a step of culturing the plant cell, and a step of recovering the culture medium of the plant cell. The method further includes isolating the glycoprotein from the culture medium and contacting the isolated glycoprotein with a sialic acid transferase to add a sialic acid residue attached to the galactose residue in the N-glycan.