1. An image processing apparatus which is configured to execute processing by allocating a plurality of weak discriminators to form a structure having at least one branch, wherein each weak discriminator comprises: a calculation unit configured to calculate a feature amount to be used in a calculation of an evaluation value of image data; and a discrimination unit configured to discriminate whether an object is included in the image data based on the evaluation value, wherein the calculation units of weak discriminators included in each of branch destinations further calculate evaluation values and the calculation unit of weak discriminators included in at least one branch destination, among the branch destinations, being decided on the basis of the evaluation values calculated for each of the branch destinations stops calculating the evaluation values.