  We report on the superconducting gap and pairing symmetry in layered
superconductor Bi4O4S3. The measurement of temperature dependence of magnetic
penetration depth was carried out using tunnel diode oscillator technique. It
is observed that Bi4O4S3 is a conventional s-wave type superconductor with
fully developed gap. The zero-temperature value of the superconducting energy
gap {\Delta}0 was found to be 1.54 meV, corresponding to the ratio
2{\Delta}0/kBTc=7.2 which is much higher than the BCS value of 3.53. In the
superconducting range, superfluid density is very well described by single gap
s- wave model.
