This seal member is a cured product of a silicone rubber composition that comprises a silicone rubber and silica particles, and has multiple insertion holes into which counterpart members are inserted; and this seal member satisfies the following conditions (a) to (d). (a) If X (parts by mass) is the content of the silica particles relative to 100 parts by mass of a base polymer of the silicone rubber, (elastic recovery rate (%))/(X (parts by mass)) is from 3.6 to 9.6. (b) The type A durometer hardness is from 15 to 30. (c) The tensile strength at break is 2.1 MPa or more. (d) The coefficient of kinetic friction of the surfaces of the insertion holes is 2.5 or less.

A composition includes a metal particle and a resin and has a wavelength band A having a wavelength band width of 1 m or more in a wavelength range of 1 to 14 m and a wavelength band B having a lower absorbance than the wavelength band A and having a wavelength band width of 1 m or more, and a ratio A.sub.min/B.sub.max between a minimum value A.sub.min of an absorbance of the wavelength band A and a maximum value B.sub.max of an absorbance of the wavelength band B is 3 or more.

This seal member is a cured product of a silicone rubber composition that comprises a silicone rubber and silica particles, and has multiple insertion holes into which counterpart members are inserted; and this seal member satisfies the following conditions (a) to (d). (a) If X (parts by mass) is the content of the silica particles relative to 100 parts by mass of a base polymer of the silicone rubber, (elastic recovery rate (%))/(X (parts by mass)) is from 3.6 to 9.6. (b) The type A durometer hardness is from 15 to 30. (c) The tensile strength at break is 2.1 MPa or more. (d) The coefficient of kinetic friction of the surfaces of the insertion holes is 2.5 or less.