To obtain a porous concrete planting foundation bed that can facilitate the introduction of trace nutrients necessary for plants and has high water retention by admixing specific active ingredients in addition to coarse aggregate, fine aggregate, binder and water-retaining material filled in continuous pores.

This porous concrete planting foundation bed contains coarse aggregate, fine aggregate, and a binder and the continuous pores in the concrete having continuous spaces are filled with a water-retention material and in addition, at least one kind of fly ash or clinker is admixed as an active ingredient. At this time, a mixture of 60-90 wt.% of normal portland cement and 10-40 wt.% of fly ash is used as a binding material for this concrete. Further, the clinker ash of ≤40 mm maximum particle size and of ≥10 mm particle size is admixed in an amount of 5-10 wt.% as a coarse aggregate for this concrete.