To provide a double-sided cylinder lock which enables a key to be operated from both the inside and the outside while serving as a lock body with one cylinder lock part.

In this double-sided cylinder lock with the lock body and the key, the lock body has one cylinder lock part and an entry which faces each of the indoor side and the outdoor side, and two engaging part groups 400 and 401 are formed in the key and each engaged with a common pin group which is composed of pins 24a, 24b and 24c. One engaging part group is formed in a position wherein respective engaging parts 40a, 40b and 40c are engaged with the respective pins 24a, 24b and 24c when the key is inserted from the outdoor side, and the other engaging group is formed in a position wherein the respective engaging parts 40a, 40b and 40c are engaged with the respective pins 24a, 24b and 24c when the key is inserted from the indoor side.