PURPOSE: To feed paste automatically by providing ultrasonic transmitter and receiver for measuring the profile of the paste.

CONSTITUTION: When a paste 7 is placed on a screen 3 and a squeegee 5 lowers to initiate rightward movement of a print head 4, an ultrasonic transmitter 10 mounted on the print head 4 transmits an ultrasonic wave which is then reflected and received by a receiver 11. Thus received ultrasonic wave is delivered to a main controller which analyzes the ultrasonic wave to recognize the profile of the paste thus detecting the amount of paste to be used in the printing. When the squeegee 5 lifts upon finish of printing operation, the amount of paste is detected again. The amount of paste is detected similarly when the squeegee 6 lowers to initiate leftward printing operation. In other words, the amount of paste is detected during printing operation and after printing operation while sustaining continuous printing operation, and when thus detected amount of paste reaches a preset residual amount, the main controller decides that the paste must be supplemented and the main controller interrupts the operation of printer, provides a supplement command to a paste feeder 12 and resumes printing operation after confirming supplement of paste. According to the constitution, residual amount of paste is detected automatically and the paste is supplemented automatically with good timing.