Since psychoanalysis bases its theory on sexuality, it is thought-provoking that strap-on (prosthesis) which meets the needs of sexual function has rarely been mentioned in psychoanalytic literature. Unless strap-on had been ignored in a way, it could easily be seen that the state of conversion to/into prosthesis is a form of psychosexual functioning. Beyond compensating for the limb deficiency, revealing the chaotic place acquired especially in psychosexual function in detail, can enable us to see the importance of prosthesis as a matter in psychoanalytic theory. We can understand prosthesis as an image of phallus, that is, the ability to be convenient for genital organ functioning in psychosexual process. The concept of “Strap-on Mother”, that is, ignorance of the phallic image in oral symbiotic phase, was developed over Freud's Schreber case. It was thought that theorists might have acquired ‘symbiotic obeisance’ as a defense in the process of reading psychoanalytic texts. This can be analogous to analyst's ignorance of the neurotic origin of maternal care demand that emerges during the therapy process. Based on the concept of Strap-on Mother, latent homosexuality, ego-self relation, determination of gender and the chaotic function of sexuality were emphasized.