A cord lock includes a female member having a first opening, a second opening, and an insertion passage for a string; and a male member entering one portion into the insertion passage from the first opening, and having, at the one portion, a male-side fastening portion to be fastened to the string inserted to pass through the insertion passage in cooperation with a female-side fastening portion formed inside the insertion passage. Fastening relative to the string is released by a pulling operation of reducing an entering amount of one portion of the male member into the insertion passage relative to the female member by gripping the string pulled out of the first opening, and by a pulling operation of reducing an entering amount of one portion of the male member into the insertion passage relative to the male member by gripping the string pulled out of the second opening.