The objectives in the present study were to evaluate the therapeutic effect of dioctahedral smectite (smectite) against piglet diarrhea caused by E. coli and Salmonella. Of this study, twenty piglets (body weight, $6.60{pm}0.34;kg$) with diarrhea were used to estimate the efficacy of smectite on piglet diarrhea with 20% smectite suspension in PBS. Pigs were administered with 1 ml smectite suspension three times a day after feeding, and fecal samples were collected at the gate of treatment and on 1st, 2nd, 3rd, and 4th day after administration. Changes in body weight, diarrhea index, and shedding of E. coli and Salmonella were monitored during the experimental period. The group treated with smectite reduced diarrhea index (p < 0.01), and increased body weight compared to control group. In the treated group, the number of E. coli and Salmonella was significantly decreased compared to each control group (p < 0.01). From results of the present study, 20% smectite suspension had therapeutic effect on diarrhea caused by E. coli and Salmonella in piglets.