We estimated the ability of aerial roots of Hedera helix 'Pittsburg' to adhere to the surface of 190mm-long wooden props with the cross section of 15mm X 15mm. On one side of the surface of a prop the 190mm-long ditch was made. The shape of the ditch was V-shaped (we called this type prop as V-prop) or rectangle (we called this type prop as R-prop). The width of the ditch in both V-prop and R-prop was 6mm or 9mm. For 84-85% of plants with V-prop, aerial roots grown toward the bottom of the V-shaped ditch, adhered to it and then extended longitudinally along it. And also for 68-74% of the p1ants with R-prop, aerial roots adhered to one of the L-shaped corners of a ditch and extended longitudinally along it. In some plants (9-23%) with either V-prop or R-prop aerial roots adhered to the flat surface of the lateral side or the bottom of the ditch and extended elliptically. These results showed that aerial roots prefer dark place such as the V-shaped valley or the L-shaped corners of a ditch, thus these results suggested the negative heliotropism of aerial roots of H. helix.