Explore ultrafast dynamics and observation methods in molecular systems through this lecture from the 10th MACS Colloquium at Kyoto University Graduate School of Science. Professor Kazuya Watanabe from the Molecular Spectroscopy Laboratory presents fundamental concepts about electron excitation state dynamics in organic solids, focusing on Chapter 1 which covers molecular ultrafast dynamics and their observation techniques. Delivered in Japanese at Science Building 6, Room 401, this presentation is part of a larger series available through Kyoto University's OpenCourseWare platform.