This thesis investigates the perception and expression of time and space concepts in the contemporary Japanese mental lexicon. Through the frameworks of cognitive linguistics and cognitive semantics it examines material obtained through a set of experiments with Japanese native speaking participants - a free word association experiment and spontaneous speech experiments on temporal and on spatial description strategies. Network analysis of the materials obtained through the free word association experiment revealed that time and space concepts are most closely related to the concepts of emotional evaluation, family/human relations and work. Qualitative and quantitative analyses of the corpora based on the material of the spontaneous speech experiments allowed me to detect the patterns of temporal and spatial description and to formulate typologies of temporal and spatial description strategies in Japanese. The findings of this work demonstrate that some of the strategies of spatial and temporal description seen in Japanese native speakers have not been described in research conducted on more extensively investigated languages. This study will contribute to the global discussion on language of time and space and will play an important role in forming deeper understanding of conceptual structure of Japanese mental lexicon.