Abstract: A segment connector to connect two segments of a modular ladder which have through holes near ends of the segments includes: a connector housing having a top open end, a bottom open end, and a side wall, the connector housing being sleeved partially over one of the two segments through one of said top and bottom open ends; a rivet insertable through rivet holes in the connector housing and the sleeved segment to pass completely therethrough to fix the connector housing sleevedly on the segment; a hook means rotatably mounted on the rivet inside the segment, the hook means including a releasing button means; and a spring means wound around the rivet and connected to the hook means to bias the hook means to project out of the connector housing; wherein, when the connector is further sleeved on the other of the two segments, the hook means normally is biased to pass holes of the segment and to project out of holes of the connector housing means, whereby the segments and the connector are firmly engaged together,