The present invention relates to a lock mechanism, and a latch device, which has a moving member that is capable of approaching and moving away from a main body, and holds said moving member to be immovable in the locked position and enables movement in the unlocked state. The lock mechanism comprises a circulating cam groove, which is formed on said main body; a trace member, which is formed roughly in an angle bracket shape and is provided to be capable of swaying on said moving member, and of which one trace part circulates following said circulating cam groove in each approaching and moving away operation of said moving member and locks the moving member in a state having coupled with a coupling part provided in the circulating cam groove. Therefore, there is no occurrence of twistingforce on the trace member. Because it is not the case that the trace part is made to circulate by causing twisting force on the trace member, there is no requirement for high measurement precision inthe circulating cam groove, and the mold expense can be reduced. Also, because twisting force is not caused on the trace member, the durability of the trace member can be improved.