To provide a weather strip of a front passenger seat side's checking window composed of seeing the outside from window glass at all times even if water comes into a door, it is dischargeable to the underside of a car after receiving it.

This weather strip is so constituted that a tongue piece 4b being contacted with a front passenger seat checking windowpane 2 attached to a door outer panel 1a of a front passenger seat of a large truck is made so as to be projectingly installed on the outer surface of a U-shaped welt part 4a to be fitted in a door reinforcing panel 1b. In this case, a water receiving lip 4c extending upward aslant toward the inner part of a car is projectingly installed in the interior side of the welt part 4a of the weather strip 4.