The invention relates to the field of washing products, and discloses a nicotinamide-containing handmade soap, which contains 0.05-10% of nicotinamide based on the weight of grease in raw materials. The preparation method comprises: (1) mixing grease and an alkali solution at a temperature of 25-50 DEG C, and carrying out stirring saponifying for 2-16 h; (2) sealing at a temperature of 15-45 DEG C, and carrying out thermal insulation until the pH value is 8-9; (3) grinding soap block into mud, adding nicotinamide or a nicotinamide composition, completely grinding, and uniformly mixing, whereinthe adding amount of the nicotinamide is 0.05-10% of the weight of the grease; and (4) molding, and placing until achieving a ripe state. According to the present invention, the handmade soap obtained by the method has effects of cleaning and moisturizing, and further has the skin care effect of nicotinamide, the nicotinamide can be stably stored in the handmade soap, and the handmade soap further has characteristics of long-term storage, no discoloration and no deterioration.