PROBLEM TO BE SOLVED: To provide an earth retaining technology for additional soil for slope greening which is excellent in construction performance and is conveniently used by a simple structure without spoiling technological advantages of prior arts. SOLUTION: An additional soil retaining device 1 includes a mountain-side horizontal frame 11 provided with a plurality of lateral lines 9 and arranged substantially horizontally to a slope surface, and a valley-side supporting frame 14 formed of a porous planar member and openably/closeably connected to a longitudinal edge of the mountain-side horizontal frame 11. The additional soil retaining device 1 is provided with an angle adjusting member 16 one end of which is rotatably connected to the valley-side supporting frame 14 and the other end of which has a hooking part capable of selectively hooking the plurality of lateral lines 9 comprising the mountain-side horizontal frame 11. By selectively hooking the hooking part formed at the end of the angle adjusting member 16 on any of the plurality of the lateral lines 9 comprising the mountain-side horizontal frame 11 according to the state of inclination of the slope surface, the mountain-side horizontal frame 11 is adjusted to be substantially horizontal. COPYRIGHT: (C)2011,JPO&INPIT