PROBLEM TO BE SOLVED: To provide an optical output monitoring device and the like capable of easily performing optical output monitoring while keeping cleanliness of a catheter.SOLUTION: An optical output monitoring device 1 comprises a light receiving part 11, an attachment part 12, an adapter 20 and a protection cap 30, and monitors power of light output from a light emission end 40a of a catheter 40 which includes an optical fiber 41 therein. The protection cap 30 has an insertion port which can make a fixed range of part of the catheter 40 at the light emission end side pass therethrough and has a window part 32 which penetrates light output from the light emission end of the catheter 40. A position of the protection cap is fixed by being inserted into the through hole of the adapter 20. A position of the adapter 20 is fixed by being attached to the attachment part 12.SELECTED DRAWING: Figure 2【課題】カテーテルの清浄度を維持したまま光出力モニタを容易に行うことができる光出力モニタ装置等を提供する。【解決手段】光出力モニタ装置１は、受光部１１、取付部１２、アダプタ２０および保護キャップ３０を備え、光ファイバ４１を内蔵するカテーテル４０の光出射端４０ａから出力される光のパワーをモニタする。保護キャップ３０は、カテーテル４０の光出射端側の一定範囲の部分の挿抜が自在な挿入口を有するとともに、カテーテル４０の光出射端から出力される光を透過させる窓部３２を有し、アダプタ２０の貫通孔に挿入されて位置固定される。アダプタ２０は、取付部１２に取り付けられて位置固定される。【選択図】図２
