Abstract: A cycle sewing machine comprises a main shaft and a clutch mechanism for connecting the main shaft to a driving source. The clutch mechanism has a breaking cam fixed to the main shaft. A breaking frame is movable to engage with the breaking cam to lock the main shaft at a predetermined position. A rotatable eccentric cam is synchronized with the main shaft. The machine further comprises a rocking link driven by the eccentric cam, an operative rod driven by the rocking link, a button holder driven by the operative rod to move vertically, and a thread trimming mechanism driven by the operative rod for cutting a thread. A drive control shaft rotates in synchronization with the main shaft to effect one rotation per cycle of sewing operation. The drive control shaft has a first control cam and a second control cam.