Oil mist separator

An oil mist separator includes: a separator body having a gas flow path; a gas introduction part introducing the blow-by gas into the separator body; a gas discharge part discharging the blow-by gas from the separator body; a separation unit separating oil from the blow-by gas; dams provided on the bottom wall of the separator body downstream of the separation unit in the gas flow path and configured to block the oil separated from flowing to the downstream side; and an oil discharge part provided upstream of the dams in the gas flow path and configured to discharge the oil separated from the separator body, wherein the dams are formed along the gas flow path so as to alternately extend from the pair of side walls, and the dams extend such that tip ends of the dams are located beyond a center of the gas flow path.