A flare event or AD Leo has been observed at Belgrade Astronomical Observatory on March $21^{st}$, 1974 during a series of patrol observations of flare stars. The observation was done with the 65-cm refractor and a D. C. polarimeter (Kubičela et al., 1976). On the basis of the obtained data a polarimetric and a photometric analysis is possible. The detection of eventual linear polarization of star radiation during a flare is certainly of great importance in interpreting the phenomenon. As few of the earlier attempts of such polarimetric observations (Oskanjan, 1964, Zappala, 1969, Grigoryan and Ericyan, 1970, Kubičela and Arseriijević, 1970,Grigoryan and Ericyan, 1971, Efimov and Shakhovskoj, 1972) and some general estimations of these (Efimov, 1970, Gershberg, 1970) were not conclusive, a new polarimetric analysis is being attempted here. The polarimetric analysis is performed bearing in mind the subtlety of such observations and a rather moderate size of the instrument utilized. Consequently, one can expect results of not very high statistical importance and a proper attention has to be paid probably only to the observed relative polarimetric changes.