Senator Sanidad was born in Narvacan, Ilocos Sur on January 17, 1897 to Cipriano Sanidad and Cayetana Casia.
He studied at Vigan High School, the University of the Philippines, the George Washington University and the National University of Washington, D.C. where he graduated with Bachelor of Laws degree and was admitted to the bar in 1928.
He was elected representative to the Philippine Legislature from the first district of Ilocos Sur in 1934 and became a member of the following committees: committees on Labor and Immigration, Aviation, Radio, Appropriations, Codes, Commerce and Industry. In 1938, he was elected Assemblyman from the same district of Ilocos Sur up to 1941.
He was married to Rosario Centeno with whom he had three children.