A study was carried out at Bangladesh Rice Research Institute, Regional Station, Rangpur along with laboratory test and farmers field in Fulgachi, Lalmonirhat for field test during Aman season with BRRI dhan52 to identify the effect of plant spacing of transplanter on grain yield. Three levels of plant spacing (30 cm×13 cm, 30 cm×15 cm, 30 cm×17 cm), seedling density setting (Middle, Middle+1 and Middle+2) and RCBD with 9 plots were used for the purpose. In field experiment, three plant spacing and Middle+2 seedling density setting was used. In this walking type self-propelled rice transplanter, the field capacity, field efficiency and fuel consumption of the transplanter were 0.134 ha hr-1 , 68 % and 3.71 L ha-1 , respectively. Labor requirement for mechanical and manual transplanting were 6.75 man ha/hr and 223 men hour per hectare respectively. Cost of mechanical transplanting was Tk. 3291 per hectare as compared to Tk.13000 per hectare in case of manual transplanting. If the usage of this machine per year decreases, the operating cost per hectare will increase. From breakeven analysis with mechanical and manual operating cost, it was found that transplanter should use at least 11 hectares per year to minimize the operation cost per hectare. For 17 cm, 15 cm and 13 cm plant spacing, number of tray requirement were 218, 270 and 277 per hectare, respectively. Number of seedling tray saved for 17 cm and 15 cm spacing were 21 % and 2.53 % compared with 13 cm spacing. In 30 cm×17 cm spacing, minimum number of seedlings required maximum no. of tray saved. Grain yield in different spacing (30 cm×13 cm, 30 cm ×15 cm, 30 cm ×17 cm) and manual transplanting were 4.43, 4.97, 5.23, 4.13 t ha-1 , respectively. Results showed that, highest grain yield among plant spacing was found 5.23 t ha-1 from 30 cm×17 cm.