A biological information measuring device includes: a case unit a first band that is a member connected to a first end portion of the case unit and a second band that is a member connected to a second end portion of the case unit at the side opposite to the first end portion. When a direction from the first band toward the second band is Y axis, a direction orthogonal to the Y axis in a plan view seen from a thickness direction of the case unit is X axis, and when a width of the first end portion in the X axis direction is a and a width of the second end portion in the X axis direction is b, the case unit satisfies a relation a
