PROBLEM TO BE SOLVED: To provide an optical probe capable of performing accurate OCT measurement with low noise, even if measuring an object having a large scattering property.SOLUTION: An optical probe 20 includes: an optical fiber 21 for transmitting light between a proximal end 21a and a distal end 21b an optical connector 22 connected with the optical fiber 21 at the proximal end 21a a light-collection optical system 23 and a deflection optical system 24 connected with the optical fiber 21 at the distal end 21b and a support tube 25 and a jacket tube 26 surrounding the optical fiber 21 and extending along the optical fiber 21. The optical fiber 21 includes a core area 41 having a refraction index n1, a first clad area 42 surrounding the core area and having a refraction index n2, a trench area 43 surrounding the first clad area and having a refraction index n3 and a second clad area 44 surrounding the trench area and having a refraction index n4. The refraction indexes have a relationship of n1>n2>n3n2>n3
