This study was conducted to investigate the seasonal variation characteristics of phytoncide in trail of Ulsan Metropolitan. Air samples were collected from May to December 2011. They were collected using Tenax Ta tube and phytoncides were detected and quantified using a Gas Chromatograph Mass Spectrometer (GC/MSD). This study are summarized as follows; The seasonal concentrations of phytoncide are Munsu Mt. 272.3 ${mu}g/m^3$, Samho Mt. 192.4 ${mu}g/m^3$, Shinbul Mt. 50.9 ${mu}g/m^3$, Sibli Bamboo forest 22.4 ${mu}g/m^3$ and Joongbu Fire Station 24.4 ${mu}g/m^3$. In Munsu Mt., Samho Mt. and Shinbul Mt. major component ratio is ${alpha}$-Pinene > ${eta}$-Pinene+Myrcene >Limonene >Camphene > ${gamma}$-Terpinene > ${alpha}$-Terpinene. Bamboo forest and Joongbu fire station major component ratio is ${alpha}$-Pinene >Limonene > ${eta}$-Pinene+Myrcene >Camphene > ${alpha}$-Terpinene. The variation of seasonal concentration is summer >spring >fall >winter. The phytoncide concentration of coniferous forest(Munsu Mt., Samho Mt.) is higher than broadleaf forest(Shinbul Mt.).