Many factors affecting directed forgetting have been studied in order to understand the processing mechanism involved. However, no research has examined the influence of subjective effort intensity on directed forgetting yet. This study used an item-method directed forgetting paradigm, using emotional words and pictures in two experiments, to investigate the psychological mechanism by which subjective effort intensity affected the directed forgetting for emotional materials. In Experiment 1, emotional words were used as stimuli in a 2×2×3 within-subjects design, with emotional valence (positive, negative), instruction (remember, forget), and effort intensity (20%, 60%, 100%) as the independent variables, and recognition rate and directed forgetting effect for emotional words as the dependent variables. In the study phase, emotional words were followed by the instructions to “remember” or “forget” with different effort intensities. The participants were instructed to process the emotional words according to the instructions and effort intensities. In the test phase, the participants were asked to recognize the old and new words. The results of the experiment showed that, regardless of positive or negative words, the harder it was to remember, the better the recognition rate. However, there was no difference in the recognition rate of positive words in the three effort intensities for forgetting, and the harder it was to forget the negative words, the more one could remember. In Experiment 2, emotional pictures were used as stimuli, and the experimental design and experimental procedure were the same as Experiment 1. The results suggested that the directed forgetting effect for emotional pictures was generally not significant. Regardless of positive or negative pictures, the higher the effort, the worse the directed forgetting effect, that is, the harder it was to forget, the more one could remember. The results of the above two experiments indicated that subjective effort intensity affected the intentional forgetting for emotional materials. Specifically, for positive words the more the efforts to try to forget, the more one could forget; whereas for negative words and pictures, the harder the efforts to try to forget, the more difficult it was to forget. This was related to the different processing methods for words and pictures, as well as the respective suitability for conscious processing and unconscious processing. In this study, the instruction to “remember” led to the selective repetition of emotional words and pictures, which accorded with the theory of selective repetition/passive decline; however, the instruction to “forget” with different effort intensities caused the active inhibition of emotional words and pictures, and this was in line with the theory of attentional inhibition/executive control.