Safety of nailing device

A safety is incorporated in a nailing device, which ensures operation safety of the nailing device. The nailing device includes a housing in which a striker plate is mounted and movable to a ready-to-strike position for subsequently striking a nail out of the housing. The safety includes a retainer pivoted to the housing with an inner end engaging the striker plate to retain the striker plate against movement to the ready-to-strike position and an opposite outer end engaging a release plate that is biased by a spring to partially projecting beyond the housing. When the nailing device is properly set on a work piece, the release plate is forced against the biasing spring back into the housing and the inner end of the retainer is caused to disengage from and thus freeing the striker plate.