A cage is made of a low carbon steel and is for use in a rolling bearing which includes an outer ring, an inner ring and a plurality of rolling elements disposed rotationally between the outer ring and the inner ring. The cage includes a plurality of pockets for retaining the rolling elements in an equi-distribution in the rotating direction of the rolling elements. The low carbon steel is a steel containing from 0.02 to 0.10% by weight of C and from 0.10 to 0.45% by weight of Mn and is subjected to plastic working. The hardness for the pocket surface at least at a portion in contact with the rolling element is Hv 190 to 270, and the hardness for the core portion in the cage section is Hv 110 to 170.