How women have represented <mother> ? This problem has been discussed in history of modern society, family, and education as well as in feminism critique. The recent social studies say modern family is the central and useful apparatus for educating modern men. <Mother> is the main existence in modern family with <child>. Women voluntarily make themselves be good <mother>, they say. The mechanism of women's self-formation to <mother> must be clarified. This paper is a case study of the theme. In Antebellum (before Civil War) America, many middle class women began reading and writing. And many books and magazines were published for women. Letters to Mothers, written by Lydia Huntley Sigourney, is one of them. Sigourney, famous as "Sweet Singer of Hartford", wrote enormous sentimental poems and stories, created "the happy mother and home", and showed the model to readers. In Letters to Mothers, "mother" is very "happy" and has "privileges". For "mother" has "precedence", "power", and "faculty of teaching" through "love". But the "privileges" or "usefulness" is showed the first with alternative interest, as contribution to women's beauty or character, and etc. "Mother's love" is not obvious in this book. Women's uneasiness, complaint, or impatience in "mother's" duty are sympathized, and soothed. And though "mother" is thought be important to educate "son" to be "good subject of a just government" (the image of "Republican Mother"), the first role of "mother" is said to educate "daughter" to be suitable to "mother". This paradox appears here and there. "Privilege" of "mother" is the rhetoric of transformation women's uneasiness to strong desire to be a empress of "the Empire of the Mother" (Ryan, M. P.). The way of discipline prevalent in Antebellum America is called "Disciplinary intimacy" (Brodhead, R. H.). It is explained as "enmeshing the child in strong bonds of love is the way authority introduces its change to its imperatives and norms". Letters to Mothers is said " (it) captures to perfection this plan's scheme of nurture and this nurture's intended goal". But we can not say so through detail analysis showed before. This woman's discourse is full of beautiful and ardent rhetoric of covering the sense of unfitness to "happy mother" of women readers. This anxiety about women readers is not appeared in men's discourse. Women's discourses to women readers, popular in this epoch, may be popular for this rhetoric. At least we can say Letters to Mothers is not consisted without this rhetoric.