There are two different types of scientists who believe in the reality of the nuclear cold fusion. The researchers, who observed the excess energy by experiments, belong to the first type. On the other hand, a small number of theoreticians, who are working on the physics of the magnetic monopole, know that the nuclear reaction of the zero incident energy proceeds when the system involves a magnetic monopole. Since the former group still lacks a theory of the nuclear cold fusion based on the first principle of the natural law, I believe it is fruitful to explain to the former group how the theoretician of the particle physics comes to arrive at the conclusion that the nuclear cold fusion must occur if a magnetic monopole exists, in the framework of the quantum theory. (C) 2007 ISCMNS. All rights reserved.