PURPOSE: To obtain an antenna measuring device which can measure a zero- point direction angle such as an electron scanning mono-pulse antenna at a high speed.

CONSTITUTION: A radio wave which is radiated from an element antenna 10-3-3 which is connected to a transmitter 1 by an RF switch 2 is received while a mono-pulse antenna 3 is rotated by a rotary stand 5. An angle of the rotary stand 5 is set by using the zero-point direction angle which is obtained as a result and then a radio wave from the element antenna 10 which is selected in sequence by the RF switch 2 is received by a sum signal output terminal 3a and a difference signal output terminal 3b. The zero-point direction angle is calculated from the obtained value.