Molecules that move like machines on the nanoscale, called "molecular machines",have been the ultimate goal of nanotechnology since Feynman advocated the concept in the 1960s. The award-winning research of the 2016 Nobel Prize in Chemistry was " Design and synthesis of molecular machines." It represents that a method to produce mechanical motions in synthesized molecules has been finally assured after half a century.
Next will be the stage of realizing unique functions that mechanical motions bring. On the other hand, with the development of molecular biology and biophysics, it has become clear that there are many proteins called "biomolecular machines" that cause mechanical motions in our bodies, and many of the life activities are supported by these molecular mechanical motion.

These are mainly responsible for producing mechanical motions by utlizing the decomposition energy of chemical substances called ATP, and converting it into another form of energy. It suggests that "moleculer mechanical motions" with the function "converting energy" can produce various functions. From the perspective of physics, it is also said that high conversion efficiency can be achived by constructing a machine with nanoscale molecules. In fact, recently, the case that converting the energy of ATP hydrolysis nearly 100% into other energy was reported.

Until now, "molecular machines" has been studied independently in chemistry, biology and physics. However, based on these backgrounds, we felt the necessity of recognizing "molecular machines" as the common concept "molecular engine" ,which has the function of enery conversion, in each field. If it is possible to establish new theory for constructing moleculer engine through active cooperation of different fields, we will be able to convert various kinds of energy utilizing tiny elements, molecules. Eventually, we can present an innovative approach. Its significance is not only in academic fields but also in society. Fortunately, we were able to gather researchers from various fields, whom share the same ambition, and were able to establish this new academic field.