NEW MATERIAL: A substd. 3-allyl-4-cyanopyrrole derivative represented by formula I [wherein R1 and R2 are each a (halogenated) 1-8C alkyl, a halogen, nitro or H or combined together to form OCF2O, R3 is a 1-8C alkyl, a cycloalkyl or benzyl and R4 is H, an alkali metal or an alkaline earth metal].

EXAMPLE: Methyl 2-[3-(2,2-difluorobenzodioxol-4-yl)-4-cyanopyrrol-1-yl]3-hydroxy acrylate.

USE: An antimicrobial agent. Especially, a control agent of plant pathogenic bacteria.

PROCESS: A compd. represented by formula II is reacted with a compd. represented by formula III (wherein R5 is an alkoxy or a dialkylamino) in the presence of a base or reacted with a separate formylating reagent to obtain the compd. represented by formula I.