In an engine rear seal installed to an engine rear portion having an end plate arranged in a motor exterior side of a housing, and a flywheel arranged in a motor exterior side of the end plate, the engine rear seal has an oil seal and a muddy water preventing seal. The muddy water preventing seal integrally has an attaching portion, and a seal lip directed to a diametrically outer side from the attaching portion and slidably coming into close contact with an end surface in the motor exterior side of the end plate. The seal lip has an inclined lip end back surface portion, and is structured such that a lip end comes into contact with the end surface at the low-speed rotating time and the lip end moves away from the end plate on the basis of an action of a centrifugal force at the high-speed rotating time.