In this paper, we discuss freezing of quantum imaginarity based on $\ell_1$-norm. Several properties about a quantity of imaginarity based on $\ell_1$-norm are revealed. For a qubit (2-dimensional) system, we characterize the structure of real quantum operations that allow for freezing the quantity of imaginarity of any state. Furthermore, we characterize the structure of local real operations which can freeze the quantity of imaginarity of a class of $N$-qubit quantum states.