Provided is a method for producing a polythiol compound, comprising: a step for reacting a polyalcohol compound represented by defined formula with thiourea in the presence of hydrogen chloride to obtain an isothiuronium salt; a step for adding, while maintaining a reaction solution containing the isothiuronium salt thus obtained at a temperature of 20\xb0 C. A production packer seals off an annulus external to the production string. The secondary coil is further coupled to the power supply so that power induced in the secondary coil causes the power supply to be charged. An offset-responsive controlling device operates for implementing one of changing a response characteristic of a loop formed by the binarizing device and the signal generating device and suspending the slice level control by the binarizing device in response to the code pattern offset information.