PURPOSE: To obtain an emulsion which is not increased in fogging even if photographic sensitivity is increased by using a specific thioether compd. at the time of production of an emulsion.

CONSTITUTION: The thioether compd. expressed by formula I is used at the time of the production of the photographic emulsion. In formula I, X denotes -OR1 or -NR2R3 (R1WR3 denote a hydrogen atom. or alkyl group) L1WL4 are an alkylene group of 1W5C; Y1 is -S- or -O-, Y2 is -S-, -O-, COO-, etc. R6 denotes a hydrogen atom. or group which can be substd.; Z denotes -COOM, -OH or -OR5 (R5 denotes a lower alkyl group, M denotes a hydrogen atom., alkali metal or quaternary ammonium salt); a1Wa3 are 0 or 1; (b) is integer in the range of 2W5; C is integer is the range of 1W3. The photographic sensitivity is thereby increased without increasing the fogging.