To inhibit the deposition at the intake of an engine by incorporating a specific deposition inhibitor into a hydrocarbon distillate.

A polyetherdiamine represented by formula I (wherein R1 to R4 are each H or a 1-4C lower alkyl; R is H or a 1-16C alkyl; and a+b is 0-80) is reacted with an aliph. carboxylic acid represented by formula II (wherein R5 is a 7-22C optionally unsatd. alkyl) to give a deposition inhibitor comprising polyetheramide represented by formula III. The polyetheramide in an amt. of 30-2,000 wt.ppm is added as the deposition inhibitor to a hydrocarbon distillate.