This paper discusses how to assess functional safety of pre-crash systems for reciprocal hazards caused by automobiles. First of all, reciprocal hazards are demonstrated by use of a pre-crash system for automobile safety, and typical architectures of the system are defined for the hazards. Next, the relationships between the failure-modes of the system and their effects upon the hazards are explored in order to describe their cause and effect logic models. Then, hazardous event rates are formulated based on the cause and effect logic models. Finally, the relationships between parameters like failure rates of the system, β-factors concerning common-cause failures, diagnostic coverage, etc., are analyzed along the functional safety standards of IEC 61508 and ISO 26262. Thus, it is concluded that this paper will provide an effective approach toward the functional safety assessment of pre-crash systems for reciprocal hazards.