Deterioration of the operation parameters of Al/SiO2/p-type Si surface barrier detector upon irradiation with alpha-particles at room temperature was investigated. As a result of 40-days irradiation with a total fluence of 8*10^9 {\alpha}-particles, an increase of {\alpha}-peak FWHM from 70 keV to 100 keV was observed and explained by increase of the detector reverse current due to formation of a high concentration of near mid-gap defect levels. Performed CV measurements revealed the appearance of at least 6*10^12 cm-3 radiation-induced acceptors at the depths where according to the TRIM simulations the highest concentration of vacancy-interstitial pairs was created by the incoming {\alpha}-particles. The studies carried out by current-DLTS technique allowed to associate the observed increase of the acceptor concentration with the near mid-gap acceptor level at EV+0.56 eV. This level can be apparently associated with V2O defects recognized previously to be responsible for the space charge sign inversion in the irradiated n-type Si detectors.