PURPOSE: To provide a ball bearing holder which has moldability, resistance against medicine, flexibility, and can easily assembled in the bearing, and also has a low heat-resistant deformation ration not damaging the bearing.

CONSTITUTION: A holder 1 for ball bearing is prepared by performing graft- denaturation with aromatic polyamide (A) composed of an aromatic dicarboxylic acid component unit (a) which is composed with a specified ration from terephthalic acid or other aromatic dicarboxylic acid component unit, and a linear fatty acid alkylene diamine component unit, (b) whose carbon number is ranged between 6 and 18, whose limiting viscosity [η] measured in concentrated sulfuric acid at a temperature of 30°C is ranged between 1.5 and 3.0d l/g, α,β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, anhydride thereof, or derivative thereof. The holder 1 for ball bearing has as its material a component made of denatured polyolefin (B) which does not contain natural polyolefin substantially and whose limiting viscosity [η]is ranged between 0.5 and 35d l/g, and glass fiber (C).