Jharkhand, thus, stretched their lead to 181 runs with three wickets remaining in the first innings at the Maharaja Bir Bikram College Stadium.
At stumps on the second day, Jaggi was batting on 165 with the help of 18 boundaries and four sixes, while Ashish Kumar was yet to open his account.
On the first day, Saurashtra were all bowled out for 277 in 78.3 overs, with Perak Mankad top-scoring with a 137-ball 96.
For Saurashtra, Kushang Patel returned figures of 3/92, while there were two wickets apiece for Jaydev Unadkat and Dharmendrasinh.
Jharkhand were overnight 29 for no loss.
Jaggi shared 136 for the fourth wicket with skipper Saurabh Tiwary (65), and 208 runs for the fifth wicket with Kishan to help his side take control of the match.