From elevators to subways, buses, and even artificial intelligence voice assistants, machines’ voices that are easily accessible in everyday life are mostly feminized. How did the machine come to have a female voice? This paper traces the process of replacing the labor of female bus attendants with mechanical devices on the bus and shows how the automatic bus announcement was made using the ‘cheerful and gentle voice of a young woman.’ By exploring the historical and social contexts driving the introduction of the civic automated bus in the 1980s, this paper challenges the view that machines came to have a friendly female voice simply because female voices are more audible than male ones. The bus attendants, later replaced by automated buses, were assigned to young women in 1960s and 1970s as they were expected to have certain types of romanticized femininity. For the further understanding of the gendered nature of machines, this paper calls for more historical studies that reveal contexts and interests behind gendered voices of machines.