A segmented core (10) for manufacturing pneumatic tires includes a substantially toroidal core body (11) formed of a plurality of core segments (12) which are arranged in a circumferential direction in tight contact with each other. A sleeve (31) rotatably supporting a first connector member (33) at its one end is inserted into the core body (11) so that the first connector member (33) is engaged with the core body (11) on one side thereof. A second connector member (40) is then detachably connected to the sleeve (31) on its another end, and thereby brought into engagement with the core body (11) on another side thereof. An integral unit is formed by the sleeve (31), the first connector member (33) and the second connector member (40), which ensures that the core segments (12) are maintained firmly and reliably connected to each other during formation and vulcanization of a green tire supported on the core body (11).