Abstract: The present invention relates to novel cephalosporins of the formula (I); ##STR1## wherein, R.sub.1 represents a C.sub.1 .about.C.sub.4 alkyl group or ##STR2## wherein, R.sub.2 and R.sub.3, independently, represent hydrogen or a C.sub.1 .about.C.sub.3 alkyl group and R.sub.4 represents hydrogen or a C.sub.1 .about.C.sub.4 alkyl group;R.sub.1a represents hydrogen or an amino-protecting group;Q represents CH or N; andthe formula ##STR3## represents a saturated or unsaturated heterocyclic group which contains 1 to 4 nitrogen atoms of which one is substituted with an amino group to form quaternary ammonium, and oxygen or sulfur, or a fused heterocyclic group thereof formed together with a substituted or unsubstituted benzene or an optional heterocyclic group, or a pharmaceutically acceptable salt thereof, to processes for preparing the same and to a pharmaceutical composition containing the same as an active ingredient.