An ethylene (co)polymer of the present invention is a (co)polymer with excellent moldability and mechanical properties and either an ethylene homopolymer or a copolymer of ethylene and an .alpha.-olefin of 4 to 20 carbon atoms. The (co)polymer has methyl branches measured by .sup.13C-NMR less than 0.1 in number per 1,000 carbon atoms and Mw/Mn measured by GPC not lower than 1.8 and lower than 4.5. The (co)polymer is either an ethylene homopolymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms. The melt tension (MT) and the swell ratio (SR) satisfy the relation; log(MT)>12.9-7.15.times.SR; and the intrinsic viscosity ([.eta.]) and the melt flow rate (MFR) satisfy the relation; [.eta.]>1.85.times.MFR.sup.-0.192 in the case of MFR<1 and the relation; [.eta.]>1.85.times.MFR.sup.-0.213 in the case of MFR.gtoreq.1. Such an ethylene (co)polymer can be usable for various molding applications and especially suitable for pipes.