Abstract: A cap flashing device for overlapping and joining two upper-end pieces of valley flashing within two valleys on a main roof is provided. An adjoining roof forms the two valleys where it meets the main roof. The device comprises a sheet of material having top and bottom surfaces and a raised triangular portion in the material and extending above the material. The triangular portion has a pair of sides in an angled relation to the remaining portion of the material with the remaining portion remaining substantially planar. Upon positioning the material upon the roof, the triangular portion is positioned over the adjoining roof and the remaining portion of the material overlapping and joining the upper end pieces of the flashing thereby inhibiting leakage in either of the valleys with the entire material in complete direct contact with the main roof with the sides being free from any folds or tucks.