Mirror syndrome (MS) is characterized by the combination of maternal generalized edema, fetal hydrops and placental hypertrophy. A shift of the serum placenta-derived angiogenic factor like sFlt-1 in MS is similar to that in pre-eclampsia (PE). We experienced a MS case caused by cardiac myopathy in the fetus with normal cardiac structure. A 27-year-old primiparous woman at 28 weeks of gestation had systemic edema without hypertension and proteinuria. Her symptoms rapidly disappeared after delivery. Compared with previously reported MS cases with maternal hypertension or proteinuria, the serum sFlt-1 level was lower in our case. Severity of maternal symptoms in MS might be paralleled with the serum sFlt-1 level. Additionally, serum hCG level in MS is much higher than that in PE. Maternal edema rather than hypertension and proteinuria can be more remarkable in MS compared with PE. It can be potentially explained by increased serum hCG level.