A measurement cell 1 includes: an opening part 106 for supplying a sample into a sample holding part 105 for holding a sample; an optical window portion for allowing light to enter the sample holding part 105 and allowing light to exit the sample holding part 105; a protection cover 101 for protecting the optical window portion, provided along the circumference of the sample holding part 105; and a first protection-cover-holding part 102 for holding the protection cover 101 at the position where the optical window portion is covered.