Recent progress in computer technology, especially in Al field, is remarkable and it enables the automation in judgment and decision-making by means of knowledge-based system. A big project on development of an intelligent ship has been carried out in Japan. It is a highly automated ship with an artificial intelligence onboard. For its realization, a thorough assessment and social acceptance is essential as well as the solution of the technical problems, because it is a large scaled system after an entirely new concept. Diversification for sense of value in modern society requires a rational procedure and concrete measures for the assessment when a new system is introduced. For the consensus it is preferable to make the measures as objective as possible. Concrete safety evaluation method has not been established yet, though it is strongly expected. An evaluation method for an automatic navigation system of the intelligent ship by means of synthetic evaluation function and computer simulation has been studied. Results of the conceptual study are presented here in Part 1. Ship safety at seas is defined by two factors. They are the potential danger of collision or stranding of the navigation area, and total ability for collision avoidance by maneuverability of the ship and skillful ship operation. Systematic approach for the safety evaluation is introduced. Both of subjective and objective aspect of evaluation are necessary for the thorough assessment. Once the factors for evaluation and evaluation function are identified, simulation results after a well-defined scenario, which contains typical ship encounters, natural and geographical conditions and some events necessary for navigation, leads indices of safety and total performance of the system by a routine procedure. These indices are objective elements of the evaluation. Hierarchical analyses for the safety and related factors based on subjective and relative evaluation between two factors, is a powerful method to build up a rational and objective evaluation function. On the other hand subjective factors are also important and essential for the safety evaluation. It is much more difficult to take the subjective elements into the evaluation. Computer graphics offer useful information for the judgment to the experts who perform the evaluation. Real time simulation with realistic models and environmental conditions is also helpful for the evaluation by experts because they can see and examine it as if a real system is working. Official standard for the safety assessment should be equipped with a sufficient scientific, social and political background. A concept for the safety assessment and its standard is shown, which is helpful for the establishment of the administrative measures by the authority of the government.