Determining reasonable assembly sequence and assembly motion sequence is important in designing an assembly line. There are many previous research in generating assembly sequences. Regarding research in generating assembly motion sequences, there are some issues to be considered. This paper devises a method to generate a basic assembly motion sequence based on an assembly sequence and a work space layout. This paper firstly clarifies “main states” derived from an assembly sequence then devises “motion sequence patterns” by comparing successive two main states. Utilizing these, this paper finally devises a basic assembly motion sequence generating method. This method is applied to two products data and verified its effectiveness.