Door weather strip and its installation structure

An installation structure including a door weather strip comprises base parts 12, 13, seal parts 14, 15 and a body part 11. The base parts 12, 13 are installed in a door trim 30 in a frontward direction from an outside of a car. The door trim 30 is furnished at the inner side of a door along the belt line BL of a car. The seal parts 14, 15 make resilient contacts with a door glass G. The body part 11 connects the base parts 12, 13 and the seal parts 14, 15. The door trim 30 is provided with a groove ditch 31 at the upper portion thereof, and the groove ditch 31 opens toward the outside of a car. A leg part(s) 32 is/are provided below the groove ditch 31 protruding below the groove ditch 31 and along the longitudinal direction of the door trim 30 continuously or intermittently. The base parts include an upper base part 12 which is forcibly inserted into the groove ditch 31 formed in the door trim 30, and a lower base part 13 which engages with the leg part 32.