To provide a planting base easily installable on a roof, etc.

The planting base unit 1 is a combination of a porous concrete block 2 having a square shape and a block-holding pan 3, and a planting base having an arbitrary area can be constructed by continuously arranging a plurality of the planting base units. The root of a plant such as lawn L is extended into the pore of the porous concrete block to fix the plant, the water collected in the pan of the block is supplied to the root and the excess water is passed through the side face of the porous concrete block to keep a proper water quantity. A low-cost material such as regenerated aggregate can be used for the porous concrete block, and the planting base can be used with a simple water-supply facility and easy control of water supply to enable the greening of the roof, etc., at a low cost.