1. A detecting device for specific subjects, comprising: an input unit for inputting images to be detected; one or more strong classifying units for carrying out strong classification to the images to be detected, each of which includes one or more weak classifying units for carrying out weak classification to the images to be detected by using a weak classifying template; a storage unit storing the weak classifying template which is used by the weak classifying unit; a judging unit judging whether or not the images to be detected contains the specific subjects according to the classification result of the strong classifying unit; wherein the detecting device for specific subjects also includes: an incremental sample input unit for inputting data for incremental learning, namely for inputting an incremental learning sample, that is to say the incremental learning sample is the undetected and wrongly detected data of the detecting device or other detecting devices for specific subjects; a learning unit for updating the weak classifying template stored in the storage unit according to the incremental learning sample inputted by the incremental sample input unit.