The orientation of unidirectional carbon fibers (UDCFs) in a manufacturing process is critical to the mechanical properties of carbon fiber reinforced plastics (CFRPs). This study presents a method to monitor the orientation of UDCFs on a mold using electrical resistance during the CFRP manufacturing process. An equivalent electrical model for UDCFs was proposed to develop an in situ sensor in a mold. The orientation of UDCFs during the CFRP manufacturing process is investigated in terms of its orthotropic electrical properties. The proposed technique can have strong implications on in situ monitoring of composite molding process where the fiber orientation is unseen by monitoring electrical resistance with Cu tapes as electrodes.