The weather warning is important disaster prevention information. Understanding of Internet users for weather warning information was researched based on Internet questionary survey in March 2013. The respondent who understood the correct meaning of a traditional weather warning was only 43%. The traditional warning is, so to speak, "plain text warning information". It is difficult to announce the risk of the disaster only by "plain text warning information". Therefore we asked about graded warning with numerical level. Respondents who chose "When a warning of level 4 was announced, I will evacuate." were 38% of all respondents. On the other hand, respondents who chose "When the super warning was announced, I will evacuate." were only 27%. The "super warning" is "plain text warning" that is equal to a warning of level 4. The answer "graded warning was simply" was 50%. On the other hand, the answer "plain text warning was simply" was 28%. It is possible that graded warning is more effective than plain text warning.
