The present invention relates to a trisoxetane compound represented by the following formula (1); wherein R1 and R3 to R8 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atom(s) with the proviso that at least one of R3 to R8 is an alkyl group having 1 to 6 carbon atom(s); R2 represents a divalent aliphatic chained organic group having 0 to 16 carbon atom(s); and R9 each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atom(s), a process for producing the same, and an optical waveguide including the same.