An optical element comprising: a container including a first end face wall and a second end face wall facing each other, a side face wall connecting the first end face wall to the second end face wall, and a hermetically sealed accommodating chamber provided inside the end face walls (24, 26) and the side face wall; a first transparent liquid having polarity or electrical conductivity and enclosed in the accommodating chamber; a second transparent liquid immiscible with the first liquid and enclosed in the accommodating chamber; a first electrode and a second electrode configured to apply an electric field to the first liquid; an insulating film between the second electrode and the second liquid; wherein the shape of an interface between the first liquid and the second liquid is changed by the application of a voltage between the first and second electrodes to form the interface having a curved surface, the center of which is a single virtual axis passing through the first end face wall and the second end face wall and extending in the thickness direction of the container, which is a direction in which the first end face wall and the second end face wall face each other, thereby refracting light traveling in a direction of the virtual axis and passing through the interface, the first electrode is provided on an inner surface of the first end face wall, the inner surface facing the accommodating chamber, the second electrode is provided on an inner surface of the second end face wall,a surface of the second electrode facing the accommodating chamber being parallel to the inner surface of the second end face wall, the insulating film is provided on the surface of the second electrode facing the accommodating chamber, and when viewed from the thickness direction of the container, an opening having a diameter the same as or smaller than the maximum diameter (DLMAX) of the interface, the center of which is the virtual axis, is provided in the second electrode or in each of the second electrode and the insulating film. a container including a first end face wall and a second end face wall facing each other, a side face wall connecting the first end face wall to the second end face wall, and a hermetically sealed accommodating chamber provided inside the end face walls (24, 26) and the side face wall; a first transparent liquid having polarity or electrical conductivity and enclosed in the accommodating chamber; a second transparent liquid immiscible with the first liquid and enclosed in the accommodating chamber; a first electrode and a second electrode configured to apply an electric field to the first liquid; an insulating film between the second electrode and the second liquid; wherein the shape of an interface between the first liquid and the second liquid is changed by the application of a voltage between the first and second electrodes to form the interface having a curved surface, the center of which is a single virtual axis passing through the first end face wall and the second end face wall and extending in the thickness direction of the container, which is a direction in which the first end face wall and the second end face wall face each other, thereby refracting light traveling in a direction of the virtual axis and passing through the interface, wherein the shape of an interface between the first liquid and the second liquid is changed by the application of a voltage between the first and second electrodes to form the interface having a curved surface, the center of which is a single virtual axis passing through the first end face wall and the second end face wall and extending in the thickness direction of the container, which is a direction in which the first end face wall and the second end face wall face each other, thereby refracting light traveling in a direction of the virtual axis and passing through the interface, the first electrode is provided on an inner surface of the first end face wall, the inner surface facing the accommodating chamber, the second electrode is provided on an inner surface of the second end face wall,a surface of the second electrode facing the accommodating chamber being parallel to the inner surface of the second end face wall, the insulating film is provided on the surface of the second electrode facing the accommodating chamber, and when viewed from the thickness direction of the container, an opening having a diameter the same as or smaller than the maximum diameter (DLMAX) of the interface, the center of which is the virtual axis, is provided in the second electrode or in each of the second electrode and the insulating film.