An optical system includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive or negative refractive power, a fourth lens unit having positive refractive power, and a fifth lens unit having negative refractive power. During focusing from infinity to the shortest distance, the second lens unit and the fourth lens unit move, the first lens unit, the third lens unit, and the fifth lens unit do not move. A predetermined condition is satisfied.