Although residues from the antibiotics found in marine products were originally examined as a pressing problem facing marine life, marine bacteria’s resistance to antibiotics has recently come to the fore as a central environmental issue. This study was conducted to examine antibiotic resistance levels among different marine samples and to show the connection between marine bacteria’s resistance to antibiotics and their exposure to microplastics. Marine bacteria were collected from coastal seawater, abyssal seawater, and coastal sand, and intestinal bacteria were collected from deep-sea fish, coastal fish, shellfish, and rotten fish; each of these samples of bacteria was tested for resistance to four types of antibiotics (meropenem, streptomycin, penicillin, and vancomycin). Among the types of bacteria collected from the coastal sand, 87.1% to 100% showed resistance to one or more of the selected antibiotics, and among the types of bacteria collected from the coastal waters, 84.6% to 100% showed antibiotic resistance. In addition, when the distribution of resistant bacteria was observed in intestinal bacteria collected from coastal and abyssal fish, the intestinal bacteria of abyssal fish had lower rates of resistance to antibiotics than that of coastal fish; moreover, 100% of versatile resistant bacteria (which showed resistance to more than three types of antibiotics) found in the intestines of coastal fish were resistant to antibiotics while, among abyssal fish, only 92% showed resistance. Among the intestinal bacteria found in shellfish and decomposing fish except for one type of sensitive bacteria, all types of bacteria were resistant to vancomycin and meropenem. Finally, as a result of culturing antibiotic-resistant bacteria with microplastics, 11 out of 12 types of bacteria developed antibiotic resistance, showing that exposure to microplastics can cause antibiotic resistance. Based on these results, it can be concluded that microplastics contribute to the development of antibiotic resistance among marine bacteria.