An oral pharmaceutical composition not containing surfactant essentially consisting of: 0.1 to 20 parts by mass of an active ingredient; 1 to 100 parts by mass of a hydrophobic liquid; 100 parts by mass of a water-soluble polymer substance; and 1 to 300 parts by mass of an excipient, wherein the active ingredient is incorporated in the hydrophobic liquid, and this hydrophobic liquid is dispersed in a composition comprising the water-soluble polymer substance and the excipient, wherein the active ingredient is one or two or more usable in combination of drugs subject to Therapeutic Drug Monitoring selected from digoxin, theophylline, procainamide, N-acetylprocainamide, aprindine, disopyramide, lidocaine, pilsicainide, propafenone, mexiletine, flecainide, quinidine, cibenzoline succinate, amiodarone, pirmenol, bepridil, phenobarbital, nitrazepam, primidone, diazepam, phenytoin, carbamazepine, zonisamide, ethosuximide, acetazolamide, clobazam, sodium valproate, trimethadione, clonazepam, sultiame, gabapentin, levetiracetam, topiramate, lamotrigine, gentamicin, amikacin, tobramycin, arbekacin, vancomycin, teicoplanin, voriconazole, cyclosporine, tacrolimus, everolimus, mycophenolate mofetil, salicylic acid, methotrexate, haloperidol, bromperidol, lithium carbonate and imatinib, or one or two or more usable in combination of an anti-cancer drug selected from cyclophosphamide, ifosfamide, melphalan, busulfan, thiotepa, nimustine, ranimustine, dacarbazine, procarbazine, temozolomide, carmustine, streptozocin, bendamustine, cisplatin, carboplatin, oxaliplatin, nedaplatin, fluorouracil, cytarabine, gemcitabine, irinotecan, nogitecan, doxorubicin, etoposide, vinblastine, vincristine, vindesine, vinorelbine, mitomycin C, doxorubicin, epirubicin, daunorubicin, bleomycin, gefitinib, erlotinib, afatinib, dasatinib, bosutinib, vandetanib, sunitinib, axitinib, pazopanib, lenvatinib, lapatinib, nintedanib, nilotinib, crizotinib, alectinib, ruxolitinib, tofacitinib, sorafenib, vemurafenib, bortezomib, sirolimus and temsirolimus, and wherein the hydrophobic liquid is one or two or more selected from benzyl benzoate, octyl decyl triglyceride, triethyl citrate, dimethyl polysiloxane, cinnamaldehyde, triacetin, piperonyl butoxide, diethyl phthalate, dibutyl phthalate, butyl phthalyl butyl glycolate and ethyl butyrate. 0.1 to 20 parts by mass of an active ingredient; 1 to 100 parts by mass of a hydrophobic liquid; 100 parts by mass of a water-soluble polymer substance; and 1 to 300 parts by mass of an excipient, wherein the active ingredient is incorporated in the hydrophobic liquid, and this hydrophobic liquid is dispersed in a composition comprising the water-soluble polymer substance and the excipient, wherein the active ingredient is one or two or more usable in combination of drugs subject to Therapeutic Drug Monitoring selected from digoxin, theophylline, procainamide, N-acetylprocainamide, aprindine, disopyramide, lidocaine, pilsicainide, propafenone, mexiletine, flecainide, quinidine, cibenzoline succinate, amiodarone, pirmenol, bepridil, phenobarbital, nitrazepam, primidone, diazepam, phenytoin, carbamazepine, zonisamide, ethosuximide, acetazolamide, clobazam, sodium valproate, trimethadione, clonazepam, sultiame, gabapentin, levetiracetam, topiramate, lamotrigine, gentamicin, amikacin, tobramycin, arbekacin, vancomycin, teicoplanin, voriconazole, cyclosporine, tacrolimus, everolimus, mycophenolate mofetil, salicylic acid, methotrexate, haloperidol, bromperidol, lithium carbonate and imatinib, or one or two or more usable in combination of an anti-cancer drug selected from cyclophosphamide, ifosfamide, melphalan, busulfan, thiotepa, nimustine, ranimustine, dacarbazine, procarbazine, temozolomide, carmustine, streptozocin, bendamustine, cisplatin, carboplatin, oxaliplatin, nedaplatin, fluorouracil, cytarabine, gemcitabine, irinotecan, nogitecan, doxorubicin, etoposide, vinblastine, vincristine, vindesine, vinorelbine, mitomycin C, doxorubicin, epirubicin, daunorubicin, bleomycin, gefitinib, erlotinib, afatinib, dasatinib, bosutinib, vandetanib, sunitinib, axitinib, pazopanib, lenvatinib, lapatinib, nintedanib, nilotinib, crizotinib, alectinib, ruxolitinib, tofacitinib, sorafenib, vemurafenib, bortezomib, sirolimus and temsirolimus, and wherein the hydrophobic liquid is one or two or more selected from benzyl benzoate, octyl decyl triglyceride, triethyl citrate, dimethyl polysiloxane, cinnamaldehyde, triacetin, piperonyl butoxide, diethyl phthalate, dibutyl phthalate, butyl phthalyl butyl glycolate and ethyl butyrate.