Police identified the man as Edward Anthony Pisarz and said his nationality was unclear.
Pol Lt Col Pasawat Siripornnopphakhun, inspector of Sattahip police station, said the accident happened at 11.20pm on the Sukhumvit Road at kilometre marker 168 in Tambon Sattahip of Sattahip district.
Pasawat said Pisarz was hit by the pickup truck after he made a U-turn.
The pickup driver, Sunthorn Sitthi, 25, said the motorcycle cut in front of him at the U-turn spot and he could not stop in time.