An electric control box (100) for an air conditioner and an air conditioner with the same are provided. The electric control box includes a housing (1); a cooling fin (2) running through the housing (1) and having a part located inside the housing (1) and another part located outside the housing (1); an inner water-guiding part (3) located inside the housing (1) and below the cooling fin (2); an outer water-guiding part (4) located outside the housing (1) and below the inner water-guiding part (3), the inner water-guiding part (3) and the outer water-guiding part (4) defining a water guide passage (a) configured to guide water (b) inside the housing (1) to the outside of the housing (1).