It is believed in Japan that only psychiatrists are capable of providing reliable psychiatric diagnosis. However, more awareness of mental health issues related to perinatal care means that midwives are now required to have psychiatric diagnostic skills. The purpose of the present paper was to examine how well Japanese midwives agreed with a psychiatrist on diagnoses of different psychiatric disorders. Vignettes of 29 cases including DSM-IV mood disorders (major depressive disorder and bipolar disorder) and anxiety disorders (generalized anxiety disorder, panic disorder, phobic disorders, and obsessive-compulsive disorder) were distributed to 12 Japanese midwives. They decided the DSM-IV diagnoses independently and compared them with those made by an expert. The kappa coefficients of the diagnoses with a base rate of 0.1 or more were moderate to almost perfect (0.64-0.83). The accuracy of symptom assessment was also satisfactory. Appropriately trained Japanese midwives can use the diagnostic criteria for psychiatric disorders reliably. It is therefore feasible to dispatch midwives who are trained in psychiatric diagnosis to antenatal clinics.