The connecting rod has a big end section divided into a body part and a cap part. The fixture bolts (21) for securing the cap part (14) to the big end part are inserted in through holes (17) in the cap part and in inner threaded holes (20) on the body side. The body-side dividing surfaces (18) are formed as unhardened parts, which have not been subjected to surface hardening treatment. The inner threaded holes (20) are blind. The dividing surfaces (18) on the body side (13) remain as unhardened parts after surface hardening treatment, in that prior to the surface hardening process they are submitted to an anti-carbon treatment. The inner threaded holes (20), which are open into these dividing surfaces, are formed in the thickness of the body part.
