We have analyzed epidemiology of pandemic influenza (H1N1) 2009 in Aichi Medical University hospital. As a result, the characteristics of pandemic influenza (H1N1) 2009 was as follows. (1) The number of ordered rapid diagnostic test was 2.8 times compared with the seasonal influenza period. The number of ordered rapid diagnostic test of the seasonal influenza period had the peak in January to March. However, the peak in pandemic influenza (H1N1) 2009 was November. Also, the number of samples on the weekend had been more than that of the weekday. (2) Positive rate of each diagnostic kit did not have the difference between the seasonal influenza (31.3 ± 1.8%) and pandemic influenza (H1N1) 2009 (29.6%). (3) Age on most ordered samples were less than ten years old, and the number of samples in 11 to 20 years old was twice in comparison with the seasonal influenza. (4) Pandemic influenza (H1N1) 2009 in influenza A accounted for 96.9%. (5) Sensitivity and specificity of ESPLINE Influenza A&B-N (FUJIREBIO, Inc., Tokyo, Japan) to the pandemic influenza (H1N1) 2009 were 100% and 100%, respectively. Also, sensitivity and specificity of prorasuto Flu (Mitsubishi Chemical Medience Corporation, Tokyo, Japan) were 77.3%and 98.5%, respectively.