Shallot is one of the vegetable crops that have a strategic role for the Indonesian economy. To increase the production of shallot, the farmers using several of input production. Changes of shallot would have an impact to output supply and input demand. This study aimed to determine the effect of changes in input and output prices to output supply and input demand of shallot farming. The study was conducted in Raji Village, Demak Subdistrict, Demak District in September - December 2016. Primary data was collected through survey method by interviewing 30 respondents. The data was analyzed in the form of input demand share by Seemingly Unrelated Regression (SUR) method. The results showed that supply of shallot is elastic to the price changes of shallot and price of seed bulbs, but less elastic to changes in labor wages and inelastic to changes in fertilizer prices. Demand for production input is elastic to the price of each input, and are largely inelastic with respect to other input prices. Therefore, to increase the shallot supply, the Government should be able to maintain the stabilization of shallot prices and encourage the use of true seed shallot as an alternative to reduce the use of shallot seeds.