The present invention relates to a shock-absorption type mower safety blade unit having a protector mounted thereon, the safety blade unit comprising: a housing fixed to a driving shaft of a driving part, provided at the end portion of an operating bar of a mower, so as to rotate together with the driving shaft； a plurality of cutter parts, which are provided at the housing, and project to the outside of the housing so as to cut weeds according to the rotation of the housing and retract to the inside of the housing so as to prevent breakage when colliding with obstacles； and an elastic part for providing elastic force to the cutter parts such that the cutter parts can return by projecting outwards when the cutter parts retract into the housing. The shock-absorption type mower safety blade unit having a protector mounted thereon, according to the present invention, prevents pebbles from being scattered or the cutter parts from being damaged because of the cutter parts retracting to the inside of the housing when colliding with the pebbles or a structure, since the cutter parts are provided to be retractable into the housing and the elastic part supports the cutter parts such that the cutter parts project outward from the housing, and improves mowing efficiency by hitting plants with greater force due to the elastic force provided from the elastic part, when colliding with large plants
