To eliminate lowering of engine performance, deterioration of an exhaust condition, etc. occurring when using biofuel by calculating a correction amount of an operation condition between when using biofuel and when using petroleum fuel to obtain a proper value of the operation condition when using the biofuel.

A fuel control device for an engine capable of combusting both biofuel and petroleum fuel includes: a biofuel type setting device 3 setting the type and mixed ratio of biofuel; a correction map 62M in which operation conditions of the engine corresponding to mixed ratios of biofuel to entire fuel; a reference map 61M in which operation conditions when using petroleum fuel are set; and an engine control device 1 creating a command map 63M for calculating a correction amount of an operation condition at the type and mixed ratio of biofuel from the correction map 62M and the reference map 61M, calculating a command value at the type and mixed ratio of biofuel based on the command map 63M and indicating the same to the engine.