1. A safety knife comprising: a knife body (10) with a cavity and an opening at a front end,

a trigger mechanism operable outside of the knife body (10) including a trigger slide (22) located in the cavity and slidable from a rear position to a front position along a longitudinal axis of the knife,

a trigger spring (23) connecting the trigger slide (22) to the knife body (10),

a blade holder (32) for securely holding a blade (31), said blade holder (32) movable along the longitudinal axis of the knife from a safety position, where the blade (31) is completely within the knife body (10), to an extended position, where the blade (10) extends out of the opening at the front end of the knife body (10), and rotatable in the extended position into a rotated position, a blade spring (33) connecting the blade holder (32) to the knife body (10) and forcing the blade holder (32) to the safety position, wherein said trigger slide (22) is equipped with a magnetic trigger coupling surface (24) formed on one side of said trigger slide and said blade holder (32) is equipped with a magnetic holder coupling surface (34) formed on one side of said blade holder,

said magnetic trigger coupling surface and said magnetic holder coupling surface face each other, said magnetic trigger coupling surface and said magnetic holder coupling surface are in contact with each other in a plane essentially parallel to the longitudinal axis of the knife body (10) and said magnetic trigger coupling surface and said magnetic holder coupling surface are connected by a magnetic coupling means force when in contact with each other, wherein movement of said trigger slide (22) from the rear position to the front position causes said blade holder (32) to move to the extended position, and

a ramp (51) is retained in the knife body (10) to move an end of the blade holder (32) into said knife body (10) when said blade holder is retracted.