A novel substance P inhibitor, spiroquinazoline [1], was isolated from the fungus Aspergillus flavipes, which was originally obtained from soil. The structure of 1 was determined by analysis of spectroscopic data and 1 was shown to contain a new carbon skeleton containing a spiro-carbon center. Also isolated from the same culture extract were the new natural product, benzodiazepiedione [3], and the known compounds, acyl aszonalenin [4], N-benzoyl-L-phenylalaninol, and seven diketopiperazines.