N-(2-amino-5-nitrobenzoyl)-o-toluidine is condensed with fluoroacetic acid or a functional derivative thereof. N-(2-fluoroacetamido-5-nitrobenzoyl)-o-toluidine obtained by said condensation reaction is dehydrated to produce 2-fluoromethyl-3-(o-tolyl)-6-nitro-4(3H)-quniazolinone, which is then subjected to reduction reaction. 2-fluoromethyl-3-(o-tolyl)-6-amino-4(3H)-quinazolinone thus obtained and a pharmaceutically acceptable acid addition salt thereof are useful as central muscle relaxants, minor tranquilizers, anti-convulsants, analgesics and/or anti-inflammatory agents.