The purpose of the present invention is to provide a safe and easily exchangeable lawn trimmer wherein a trimmer blade mounted in a rotational housing has a large rotation radius and a protection cover mounted on the rotational housing is supported by a bearing and configured to be rotated so that workability is improved by increasing the operation radius of the trimmer blade, and wherein materials capable of causing risk under the rotational housing, such as small stones or grass, are prevented from interfering with the rotation of the rotational housing or the operation of the trimmer blade. In particular, another purpose of the present invention is to provide a safe and easily exchangeable lawn trimmer wherein not only is a trimmer blade always supported by a predetermined elastic force during operation to pre-empt accidents caused by excess rotation of the trimmer blade, but breakages or noise caused by collision with other components during lawn cutting are also prevented, to facilitate stable lawn cutting. Further, yet another purpose of the present invention is provide a safe and easily exchangeable lawn trimmer wherein a trimmer blade can be conveniently and rapidly exchanged and used since the trimmer blade can be mounted in a rotational shaft of a conventional trimmer by merely releasing fastening bolts by which the blade is rotatably supported.Lobjet de la présente invention est de fournir un coupe-herbe sûr et facilement remplaçable dans lequel une lame de tondeuse montée dans un logement rotatif présente un grand rayon de rotation, et un couvercle de protection monté sur le logement rotatif est supporté par un palier et conçu pour être entraîné en rotation de sorte que la maniabilité est améliorée par augmentation du rayon de fonctionnement de la lame de tondeuse, et dans lequel des matériaux pouvant représenter un risque sous le logement rotatif, tels que de petites pierres ou de lherbe, sont empêchés dinterférer avec la rotation du logement rotatif ou
