The present invention relates to an indoor greening system enabling space utilization to produce various spaces, whereby the system can be installed indoors and outdoors through only simple assembly and freely enlarged in multiple stages according to a purpose, and can uniformly maintain and automatically manage the supply of moisture to reduce the effort and costs for planting and greening. The indoor greening system enabling space utilization of the present invention, which can provide the above purposes and effects, comprises: a flowerpot unit (10), a water storage sponge (30), and a planting soil (20). In the flowerpot unit (20), a lower portion is narrowly inclined; an opened upper side is horizontally or frontally inclined at 45° or lower; a rear portion protrudes higher than a front portion; and an end portion of a hanger protrusion (14) at the rear portion has a hanger stepped portion (16) such that the hanger protrusion (14) is caught on and fixed to an indoor structure (90), such as the wall or ceiling. The water storage sponge (30) is provided at a lower portion inside the flowerpot unit (10). A predetermined amount of water supplied from the outside is stored in the water storage sponge (30), and slowly supplied to planted vegetation (40) through a capillary phenomenon. The plant soil (20) is provided above the water storage sponge (30) inside the flowerpot unit (10) such that the vegetation (40) can be planted and grown.