This is the age where babies learn object permanence--if you leave, are you still there? will you come back? Separation anxiety usually doesn't start until babies are older than this. So I'm guessing he is crying just to communicate. Crying is his language, and chances are he'd holler out, "Take me with you this time!" if he could. Also, the reason he does this with *you* is because babies attach to one primary caregiver, which is usually the mother-figure, hence you. The good news is babies grow out of this developmental phase. In the meantime, it is okay to hold him, take him with you, and reassure him. Maybe he'll move through it quicker!