1. A cephalosporin derivatives of the general formula ##STR1## wherein R.sup.1 is an .alpha.-, .beta.- or .gamma.-amino acid residue (bonded by the ester linkage), which may optionally be substituted by one or two lower alkyl groups at the amino group thereof, R.sup.2 is an 1-alkanoyloxyalkyl, 1-alkoxycarbonyloxyalkyl, phthalidyl or 5-methyl-1,3-dioxolen-2-on-4-ylmethyl group, R.sup.3 is a carbamoyloxymethyl group, which may optionally be substituted by one or two lower alkyl groups, or a heterocyclothiomethyl group, which may optionally be substituted by one or more appropriate substituents, and R.sup.4 is a hydrogen atom or a hydroxy group, or its non-toxic salt are found to be useful as orally administrable antibiotics having broad antimicrobial activities against both gram-positive and gram-negative bacteria.