We report the analysis of Fermi Large Area Telescope data from five years of observations of the broad line radio galaxy 3C 120 .
The accumulation of larger data set results in the detection of high-energy \gamma -rays up to 10 GeV , with a detection significance of about 8.7 \sigma .
A power-law spectrum with a photon index of 2.72 \pm 0.1 and integrated flux of F _ { \gamma } = ( 2.35 \pm 0.5 ) \times 10 ^ { -8 } \ > \mathrm { photon\ > cm } ^ { -2 } s ^ { -1 } above 100 MeV well describe the data averaged over five year observations .
The variability analysis of the light curve with 180- , and 365- day bins reveals flux increase ( nearly twice from its average level ) during the last year of observation .
This variability on month timescales indicates the compactness of the emitting region .
The \gamma -ray spectrum can be described as synchrotron self-Compton ( SSC ) emission from the electron population producing the radio-to-X-ray emission in the jet .
The required electron energy density exceeds the one of magnetic field only by a factor of 2 meaning no significant deviation from equipartition .