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東日本大震災を受けて，災害時に人々が避難施設まで円滑な避難行動を行うことの重要性が再確認された．1日の乗降者数が300万人を超える新宿駅などの密集地からの避難においては，各密集地からの避難により新たに人が密集する道路が発生し，円滑な避難行動が困難になる可能性が高い．また，その道路の周辺の地理的条件によっても，影響を受けると予想される．そこで，本論文では，新たに密集する道路と地理的条件を考慮し，道路ネットワークを用いて災害時において避難リスクの高い経路を発見する手法を提案する．さらに，時間ごとに人々が密集する場所が変化することも考慮し，1時間ごとに避難リスクの高い経路を可視化し，考察する．, The 2011 Tohoku earthquake and tsunami showed the importance of smooth evacuation to nearby safe evacuation facilities. Smooth evacuation from crowded areas like train stations is difficult because people facing disaster often cannot find good paths to the nearest safe places and their evacuation may create congestion, which again hinders smooth evacuation. For smooth evacuation, the safety of roads used for evacuation needs to be evaluated. This evaluation requires 1) geographical characteristics of roads such as the risk of collapse of neighboring buildings and road width and 2) crowdedness of roads at the moment of disaster. While previous studies considered the former, the latter information has not been well studied because the crowdedness depends on the demographics of a city, which is quite dynamic and difficult to measure. For example, daytime and nighttime populations of a city differ greatly. This paper proposes a method that measures demographic snapshots of a city from time- and geo-stamped micro-blog posts and visualizes high-risk evacuation roads on the basis of geographical characteristics and demographics. Our method enabled visualization of high-risk evacuation roads on a per-hour basis. We also qualitatively analyze and discuss the visualization results.