Wheel rolling bearing apparatus

A wheel rolling bearing apparatus comprising:

• an outer race member which comprises a first flange portion including a bolt hole and a second flange portion including a bolt hole which are projected on an upper portion side and a lower portion side, respectively, and which is attached to a vehicle side via the first and second flange portions;
• an inner race member which is disposed inwards of an inner circumference of the outer race member and to which a wheel is attached;
• a plurality of rolling elements which are interposed between the outer race member and the inner race member;
• a first reinforcement portion which is projected on at least a proximal end portion of the first flange portion to reinforce the proximal end portion by connecting the proximal end portion with an outer circumferential surface of the outer race member, the first reinforcement portion lies on both sides of the bolt hole,
• wherein an upper surface, which connects the proximal end portion of the first flange portion with the outer circumferential surface of the outer race member, of the first reinforcement portion comprises a convex curve in an axial section of the outer race member, and
• wherein a boundary between the first reinforcement portion and the first flange portion extends at a radially inner side of a radially inner most part of the bolt hole.