To obtain that shows excellent transparency, staining resistance and flexibility by admixing a specific amount of a specific component and polymerizing the resultant monomer mixture.

The polymer prepared by polymerizing a monomer mixture is used as a lens material for eyes that comprises (A) 20-50 wt.% of a silicon- containing alkyl acrylate, (B) 20-50 wt.% of a polysiloxane macromonomer of formula I {A1 is formula II (Y21 is acryloyloxy; R31 is a 2-6C alkylene); U1 is formula IV (X21 0 or the like; E21 is a divalent group originating from diisocyanate; X25 is 0 or the like; R32 is a 1-6C alkylene); S1 and S2 are formula V (R23, R24, R25, R26, R27, R28 are each a 1-3C alkyl or the like; K is 1-1,500; L is 0-1,500); U2 is formula IV (R37 and R38 are each a 1-6C alkylene; X27 and X28 are each 0 or the like; E24 is a divalent group originating from diisocyanate); U3 is formula VII (R33 is a 1-6C alkylene; X26 is 0 or the like; E22 is a divalent group originating from diisocyanate)}, (C) 10-50 wt.% of hydroxyalkyl (meth) acrylate and (D) 0.01-10 wt.% of a crosslinkable compound.