The invention provides a band and a biological information measurement device. A band for mounting a device main body includes first and second band portions which are connected to device main body, wherein the ratio between the widths of the first band portion and the second band portion in a second direction intersecting a first direction in which the first band portion and the second band portion extend from the device main body and the width of the device main body in the second direction is greater than or equal to 0.5 and less than or equal to 1.4.