To provide an air cleaning greening device for estimating a dry state (moisture content) of a planting board on the basis of temperature and air flow in an installation environment in operation, then performing watering to the planting board on the basis of the estimation result, and a control method thereof.SOLUTION: The air cleaning greening device comprises: a planting unit storing the planting board； a ventilation device； a watering device； first storage means for storing a relational expression between a moisture content on the planting board on a plurality of depth levels in a vertical direction from an upper end of the planting unit and a time； second storage means for storing a relational expression between a watering amount and permeation depth； and control means of the watering device. A constant time watering control performs a prescribed amount of watering at a preset time, and calculates a time T until reaching to an optional moisture content since a time on the optional depth (Y) on the planting board, using the relational expression of the first storage means, a measurable watering control calculates a watering amount permeating to the optional depth (Y) on the planting board using the relational expression of the second storage means, then performs watering at a time when the time T passes since said time.SELECTED DRAWING: Figure 8【課題】運転時における設置環境の温度と風量とから植栽基盤の乾燥状態（含水率）を推定し、係る推定結果に基づいて植栽基盤に灌水を行う空気清浄緑化装置および空気清浄緑化装置の制御方法を提供する。【解決手段】植栽基盤を収納した植栽ユニットと、通風装置と、灌水装置と、植栽ユニット上端から垂直方向の複数の深度の植栽基盤における含水率と時間との関係式を記憶しておく第一記憶手段と、灌水量と浸透深度との関係式を記憶しておく第二記憶手段と、灌水装置の制御手段を備え、定時灌水制御は、予め設定した時刻に所定量の灌水を行うとともに、任意の深度（Ｙ）の植栽基盤における時刻から任意の含水率に達するまでの時間（Ｔ）を、第一記憶手段の関係式を用いて演算するものであり、臨時灌水制御は、任意の深度（Ｙ）の植栽基盤にまで浸透する灌水の量を、第二記憶手段の関係式を用いて演算して、時刻から時間（Ｔ）が経過した時刻に灌水を行う。【選択図】図８
