The suitability of raspberry cultivars for machine harvesting or transport is mainly connected with the physical characteristic of fruit. This report presents results of the mechanical strength of raspberries fruit, at different ripeness class, obtained using several measuring methods. The loading tests of single berry subjected to uniaxial loading were performed with the Instron machine. The compression tests were performed on a single drupe of raspberry and penetrometers of 1-7 mm diameters were used. The cohesion force and the detachment force, the values which are very important for the mechanical harvest, were registered at tension tests. The ripeness stage had a distinct effect on the mechanical strength of all varieties and clones of raspberries. The damage force observed during penetration with each size of penetrometer was higher for the I class, however, for 7 mm penetrometer only, the force was more than five times higher than for III class. With an increase of fruit ripeness of 80261 Clone, the cohesion force registered during tension test decreased from 0.53 N for I ripeness class to 0.14 N for III ripeness class. The detachment force noticed at tension tests for I class of ripeness, with red colour present, was four times higher than for both the II and III classes of maturity. The compression and tension tests for single fruit are adequate for the estimation of mechanical properties and correctly reflect the maturity stage of raspberry.