It is intended to provide a method of constructing a coffee plant with a lowered caffeine content by regulating the expression of genes encoding enzymes relating to caffeine biosynthesis, which are isolated from coffee, b y the antisense method or the RNAi method. Namely, a method of constructing a caffeineless coffee plant by genetic recombination which involves the step o f preparing an antisense sequence or an RNAi sequence of a gene encoding an enzyme relating to caffeine biosynthesis and thus constructing an expression vector for transformation, the step of transferring the expression vector th us obtained into an agrobacterium, the step of infecting a tissue piece wherein cell division of a coffee plant has been activated, or a callus or an adventive embryo derived from a coffee plant tissue piece with the above agrobacterium to thereby transform the tissue piece, callus or adventive embryo as described above, and the step of obtaining a transformed coffee plant from the thus transformed tissue piece, c
