a light source unit including a plate-shaped substrate member which has flexibility and has a circuit pattern on a first surface of the substrate member, a light-emitting diode (LED) on the first surface of the substrate member, and a temperature sensor on the first surface of the substrate member, which is configured to measure a temperature generated when the LED emits light;

a pair of cover members disposed on the first surface and a second surface of the substrate member to prevent the light source unit from being exposed to an outside;

a connection cable configured to supply the light source unit with power supplied from the outside and

a current applying member configured to apply current to a user's skin,

wherein the connection cable comprises a control unit configured to control operation of the light source unit,

wherein the control unit controls an on/off operation of the light source unit based on temperature information transmitted from the temperature sensor,

wherein the pair of cover members includes a first cover member which covers the LED and is transparent, and a second cover member which is translucent or opaque, and

wherein the current applying member is disposed on an outer surface of the first cover member.