A polyethylene spacer for optical fiber cable including a central tensile member, an intermediate coating layer arranged on an outer periphery of the central tensile member and being compatible with polyethylene and a main coating arranged on an outer periphery of the intermediate coating layer and having continuous spiral grooves for accommodating optical fibers and which are inverted periodically in a lengthwise direction. The main coating is formed from polyethylene resin. The spacer includes ribs defining the spiral grooves. A minimum thickness of the ribs is 1.0 mm or less, the groove inclination angle &agr; of a cross section of the spacer at inversion part is 18° or less. A resin density of a root part of each rib is the lowest in comparison to a resin density at a tip part of the rib and central parts of the rib between the root part and the tip part.