An optical imaging lens includes first, second, third, and fourth lens elements arranged in order from an object side to an image side along an optical axis. Each lens element has an object-side surface and an image-side surface. The first lens element has positive refracting power. The object-side surface of the first lens element has a convex portion in a vicinity of the optical axis. The second lens element has refracting power. At least one of the object-side surface and the image-side surface of the third lens element is an aspheric surface. The object-side surface and the image-side surface of the fourth lens element are both aspheric surfaces.