Test kit

A test kit for detecting a substance to be detected a liquid sample, the test kit comprising:

• a first member, the first member comprising a dropping region located furthermost upstream onto which the liquid sample is dropped, a labeling substance holding region comprising a containing portion and a non-containing portion, and a backflow prevention region, wherein:
• the containing portion contains a labeling substance consisting of a label and a binding substance that binds the substance to be detected wherein the label is immobilized on the binding substance;
• the non-containing portion is located upstream of the containing portion and does not contain the labeling substance;
• the backflow prevention region is composed of a fibrous member material having finer opening size than the fibrous member material at the dropping region and the labeling substance region, the backflow prevention region further comprising a compressed region of the first member;
• and
• the backflow prevention region is located between the dropping region and the non-containing portion of the labeling substance holding region, the backflow prevention region separated from the containing portion by the non-containing portion;
• and
• a second member comprising a detection zone for capturing the labeling substance, wherein:
• the labeling substance is captured through the substance to be detected;
• and
• the second member is downstream of the first member in the developing direction and the upstream end of the second member is in contact with the labeling substance holding region of the first member, thereby allowing the labeling substance to flow with the liquid sample from the first member to develop at the detection zone at the second member.