A contact probe is conductive and capable of expanding/contracting along an axial line direction. The contact probe includes: a first contact member configured to contact one contact target; a second contact member configured to contact another contact target, and to house at least a portion of the first contact member; and a spring member configured to couple the first contact member and the second contact member in a manner capable of expansion/contraction with both end parts of the spring member. The spring member is wound in a helical shape, and at least a diameter of an outer circumference in one of the end parts held by the second contact member is larger than diameters of other portions. A diameter of an inner circumference of an end part of the second contact member on a side housing the first contact member is equal to or larger than a maximum diameter of the first contact member.