Police said the accident happened at 10pm on the Khanom-Klong Leng road in Ban Khao Hua Yoi in Tambon Khuan Thong, Khanom district.
The couple were identified as Chamnarn Chuphan, 59, and his wife, Suwanna Thinraya, 44.
The bus driver, Ananchai Kongchan, 35, waited for police at the scene to face a charge for alleged reckless driving causing deaths.