We have conducted an observation towards the nucleus of a type-1 Seyfert, NGC 1097 in ALMA Cycle 0 with Band 7. The results of this observations are summarized as follows: (1) No vibrationally excited HCN emission has been detected. This indicates that the IR pumping is not the cause of HCN enhancement in this galaxy. (2) We found an extremely high HCN(J=4-3) to CS(J=7-6) line ratio, which is over 10. A similar ratio (similar to 10) was also found in NGC 1068 (AGN). However, such high ratios have never been observed in starburst galaxies and Galactic star-forming regions. Therefore, we regard this line ratio as an effective discriminator between AGN and starburst activity.